3.5.2.6 A123C stability towards cloxacillin not enhanced -, 209364 3.5.2.6 A172E random mutagenesis 733117 3.5.2.6 A172P random mutagenesis 733117 3.5.2.6 A172T random mutagenesis 733117 3.5.2.6 A172V random mutagenesis 733117 3.5.2.6 A233V naturally occuring genetic variant 734041 3.5.2.6 A751G in the ampC gene from strain Y56 the A751G mutation is responsible for the inactivation of beta-lactamase -, 665324 3.5.2.6 A751G inactive -, 665324 3.5.2.6 A751G mutant, inactive -, 665324 3.5.2.6 A77C stability towards cloxacillin not enhanced -, 209364 3.5.2.6 C221S mutant catalytic activity on the burst phase is similar to that of the wild type BcII -, 699013 3.5.2.6 C69F random mutagenesis 733117 3.5.2.6 C69Y random mutagenesis 733117 3.5.2.6 D104A km for benzylpenicillin and methicillin increased 2 fold, no change in catalytic activity -, 209347 3.5.2.6 D104E mutation results in a 1000fold enhancement in binding affinity to beta-lactamase inhibitor protein BLIP, as it restores a salt bridge to BLIP. Mutation of a neighboring residue, BLIP E73M, results in salt bridge formation between SHV-1 D104 and BLIP K74 and a 400fold increase in binding affinity. BLIP F142 cooperatively stabilizes both interactions 721004 3.5.2.6 D120A kcat/KM is up to 425000fold lower than the wild-type enzyme. Ki-value for phosphate is 450fold lower than wild-type value 665627 3.5.2.6 D120A site-directed mutant of CphA, generated and characterized 696094 3.5.2.6 D120C site-directed mutagenesis, reduced activity and metal binding compared to the wild-type enzyme 656274 3.5.2.6 D120E kcat/KM is up to 136000fold lower than the wild-type enzyme. the Zn-Zn distance is increased by 0.3 A compared with wild-type enzyme 665627 3.5.2.6 D120N site-directed mutagenesis, reduced activity and metal binding compared to the wild-type enzyme 656274 3.5.2.6 D120S site-directed mutagenesis, reduced activity and metal binding compared to the wild-type enzyme 656274 3.5.2.6 D120T site-directed mutant of CphA, generated and characterized 696094 3.5.2.6 D130G/M154L naturally occuring genetic variation 734041 3.5.2.6 D130N/M154L naturally occuring genetic variation 734041 3.5.2.6 D170N increase in Ki-value for clavulanic acid, little difference in the hydrolytic profile of beta-lactams compared to wild-type,no ceftazidime hydrolysis 663653 3.5.2.6 D176G random mutagenesis 733117 3.5.2.6 D176N random mutagenesis 733117 3.5.2.6 D179G activity unchanged or enhanced -, 209346 3.5.2.6 D179N activity unchanged or enhanced -, 209346 3.5.2.6 D179N random mutagenesis 733117 3.5.2.6 D223A site-directed mutagenesis, the mutation does not signifcantly affect resistance of the cells against antibiotics -, 756926 3.5.2.6 D66A site-saturation mutagenesis at position 66, 8fold increase in minimum inhibitory concentration for ceftazidime compared with the wild type (0.25 to 2 microg/ml). Mutation results in only minor changes in steady-state protein levels 696086 3.5.2.6 D66C site-saturation mutagenesis at position 66. Expression of this variant is diminished relative to that of the other proteins 696086 3.5.2.6 D66L site-saturation mutagenesis at position 66, rise in resistance against ceftazidime compared with the wild type 696086 3.5.2.6 D66M site-saturation mutagenesis at position 66, rise in resistance against ceftazidime compared with the wild type. Mutation results in only minor changes in steady-state protein levels 696086 3.5.2.6 D66N site-saturation mutagenesis at position 66, mutation leads to a moderate enhancement of extended-spectrum cephalosporin resistance and an increase in cefepime and cefotaxime resistance. Mutation results in only minor changes in steady-state protein levels 696086 3.5.2.6 D66P site-saturation mutagenesis at position 66 696086 3.5.2.6 D66W site-saturation mutagenesis at position 66, mutation results in only minor changes in steady-state protein levels 696086 3.5.2.6 D66Y site-saturation mutagenesis at position 66, mutation results in only minor changes in steady-state protein levels 696086 3.5.2.6 D95N naturally occuring genetic variation 734041 3.5.2.6 DELTA1-17 mutant lacking the first 17 residues, first alpha helix, reduced activity, no hydrolysis of cloxacillin -, 209364 3.5.2.6 E104K E104M increased kcat -, 209359 3.5.2.6 E104K side directed mutagenesis -, 695638 3.5.2.6 E104K/G238S - -, 209359 3.5.2.6 E104M/G238S E104M/G238S 1000 fold higher hydrolysis of cefotaxime -, 209359 3.5.2.6 E152A site-directed mutagenesis, the mutant shows highly declined resistance to antibiotics compared to wild-type NDM-7 -, 756926 3.5.2.6 E152A/S191A site-directed mutagenesis, the double mutant shows 2fold reduced antibiotic resistance compared to single mutants, but substantially declined resistance compared to wild-type NDM-7 756926 3.5.2.6 E152C ImiS mutant (ImiS[E152C]) is generated by mutating the imiS gene in pET26bimiS. Mutant exhibits very similar kinetic behavior to wild type 698477 3.5.2.6 E152K naturally occuring genetic variation 734041 3.5.2.6 E162A site-directed mutagenesis, mutation of the an omega loop glutamate, the mutant shows reduced activity against penicilin and cepahlosporin antibiotics in recombinant Escherichia coli cells and reduces the resistance level of the cells -, 756741 3.5.2.6 E164A site-directed mutagenesis, mutation of the an omega loop glutamate, the mutant shows highly reduced activity against penicilin and cepahlosporin antibiotics in recombinant Escherichia coli cells and potently reduces the resistance level of the cells -, 756741 3.5.2.6 E166A SHV deacylation deficient enzyme 685183 3.5.2.6 E166A site-directed mutagenesis, inactive mutant. The Glu166Ala mutant form of BlaC has no hydrolytic activity and forms a stable acyl-enzyme complex that can be structurally characterized, suggesting that Glu166 is required for deacylation and product release -, 733340 3.5.2.6 E166C mutant constructed to obtain an engineered beta-lactamase that contains an environment-sensitive fluorophore conjugated near its active site to probe the structural dynamics of the omega-loop and to detect the binding of substrates. Mutant enzyme carrying a 6-bromoacetyl-2-dimethylaminonaphthalene label shows improved binding kinetics and positive fluorescence signal toward oxyimino-cephalosporins, but shows little such effect to non-oxyimino-cephalosporins. The omega-loop adopts a less stabilized structure, and readily undergoes conformational change to accommodate the binding of bulky oxyimino-cephalosporins while no such change is observed for non-oxyimino-cephalosporins 719960 3.5.2.6 E166D random mutagenesis 733117 3.5.2.6 E166G random mutagenesis 733117 3.5.2.6 E166K random mutagenesis 733117 3.5.2.6 E167A site-directed mutagenesis, mutation of the an omega loop glutamate, the mutant shows reduced activity against penicilin and cepahlosporin antibiotics in recombinant Escherichia coli cells and reduces the resistance level of the cells -, 756741 3.5.2.6 E168del random mutagenesis 733117 3.5.2.6 E193A site-directed mutagenesis, the mutant shows 30% reduced activity compared to the wild-type enzyme. In vivo expression of 4455E193A reduces the beta-lactam resistance for penicillin and ampicillin by twofold as compared to the expression of wild-type MSMEG_4455 -, 758284 3.5.2.6 E240V side directed mutagenesis -, 695638 3.5.2.6 E240V substitution increases catalytic efficiency toward ceftazidime -, 695638 3.5.2.6 G240H kcat/Km for cefotaxime is 5fold higher than wild-type value, kcat/Km for cephalothin is 6.4fold higher than wild-type value, kcat/Km for cefazolin is 2.3fold higher than wild-type value, kcat/Km for benzylpenicillin is 3.9fold lower than wild-type value 713474 3.5.2.6 G69S/A74T/G200R naturally occuring genetic variation 734041 3.5.2.6 G984A inactive -, 665324 3.5.2.6 G984A mutant, inactive -, 665324 3.5.2.6 H116C site-directed mutagenesis. Mutant binds 0.33 equiv of Zn2+ 698463 3.5.2.6 H118A site-directed mutant of CphA, generated and characterized, H118A and H196A mutations lead to a decrease of at least 1000fold in activity against carbapenems compared with the wild-type enzyme 696094 3.5.2.6 H118C site-directed mutagenesis 698463 3.5.2.6 H121C site-directed mutagenesis. Mutant binds 0.11 equiv of Zn2+ 698463 3.5.2.6 H196A site-directed mutant of CphA, generated and characterized, H118A and H196A mutations lead to a decrease of at least 1000fold in activity against carbapenems compared with the wild-type enzyme 696094 3.5.2.6 H196C site-directed mutagenesis 698463 3.5.2.6 H263A site-directed mutant of CphA, generated and characterized 696094 3.5.2.6 K104E thermal stability is increased, mutant enzyme loses activity against oxyimino-cephgalosporins, aztreonam, and ampicillin 663648 3.5.2.6 K216A site-directed mutagenesis, the mutation does not signifcantly affect resistance of the cells against antibiotics -, 756926 3.5.2.6 K224Q site-directed mutant of CphA, generated and characterized 696094 3.5.2.6 K226Q site-directed mutant of CphA, generated and characterized 696094 3.5.2.6 K232N increase in Ki-value for clavulanic acid, little difference in the hydrolytic profile of beta-lactams compared to wild-type 663653 3.5.2.6 K234A no significant structural change, mutant with decreased Km 1-2 orders of magnitude and kcat 2-3 orders of magnitude 209369 3.5.2.6 K234E no significant structural change, mutant with decreased Km 1-2 orders of magnitude and kcat 2-3 orders of magnitude 209369 3.5.2.6 K73A site-directed mutagenesis, inactive mutant, substrate/inhibitor binding structure -, 733349 3.5.2.6 K73A site-directed mutagenesis, inactive mutant. The Lys73Ala mutant form of BlaC permits the structural identification of the Michaelis complex, but has no catalytic activity, indicating Lys73 is essential for the acylation step -, 733340 3.5.2.6 L162F random mutagenesis 733117 3.5.2.6 L169P random mutagenesis 733117 3.5.2.6 L169Q random mutagenesis 733117 3.5.2.6 L169R random mutagenesis 733117 3.5.2.6 L316I substitution is located within the R2 loop that is considered the hotspot region responsible for the extended substrate spectrum in class C beta-lactamases -, 698303 3.5.2.6 M154L naturally occuring genetic variation 734041 3.5.2.6 M154L/G222D naturally occuring genetic variation 734041 3.5.2.6 M182T side directed mutagenesis -, 695638 3.5.2.6 M182T/T195S/A224V mutant selected by a directed evolution strategy. It is allosterically downregulated by Zn2+, Ni2+ and Co2+ with binding affinities around 300 microM 720961 3.5.2.6 additional information a VIM-2 enzyme inserted in integron In58, in an isolate from a female cystic fibrosis patient, is resistant to all antimicrobial agents tested except colistin, this isolate presented a unique random amplified polymorphic DNA, RAPD, type, overview 692627 3.5.2.6 additional information analysis of 516 mutated enzymes that acquired the ceftazidime-hydrolyzing activity, and identification of twelve positions with single amino acid substitutions, co-localized at the active-site pocket area. single amino acid substitutions are found at positions C89, N136, L162, R164, E166, L169, N170, T171, A172, P174, D176, D179. All substitutions cause a congruent effect, expanding the space in a conserved structure called the omega loop, which in turn increased flexibility at the active site 720866 3.5.2.6 additional information construction of diverse mutant of the beta-lactamase inhibitor protein BLIP by alanine scanning mutation 656249 3.5.2.6 additional information construction of diverse mutants of the beta-lactamase inhibitor protein BLIP by alanine scanning mutation 656249 3.5.2.6 additional information gene knockout mutant, KJDELTAL1. Induction of the L1 and L2 genes is differentially regulated -, 695630 3.5.2.6 additional information gene knockout mutant, KJDELTAL2. Induction of the L1 and L2 genes is differentially regulated -, 695630 3.5.2.6 additional information generation of an enzyme-deletion mutant of strain CIP104536 -, 734040 3.5.2.6 additional information identification of blaSHV gene mutants SHV-2a, SHV5 et SHV1, that do not seem to be ESBLs, overview 694543 3.5.2.6 additional information identification of two variants that confer elevated resistance to cefotaxime but decreased resistance to other antibiotics. These variants are circularly permuted in the omega-loop proximal to the active site. One variant is circularly permuted such that the key catalytic residue Glu166 is located at the N-terminus of the mature protein 720861 3.5.2.6 additional information insertion of a circularly permuted TEM-1 beta-lactamase gene into the maltose binding protein leads to protein RG13, which exhibits allostery. RG13 is positively regulated by maltose yet is inhibited by Zn2+ at low millimolar concentration. The structure reveals that the maltose binding protein and TEM-1 domains are in close proximity connected via two linkers and a zinc ion bridging both domains. By bridging both TEM-1 and MBP, Zn2+ acts to twist tie the linkers thereby partially dislodging a linker between the two domains from its original catalytically productive position in TEM-1. This linker 1 contains residues normally part of the TEM-1 active site including the critical beta3 and beta4 strands important for activity. Mutagenesis of residues comprising the crystallographically observed Zn2+ site only slightly affect Zn2+ inhibition 2- to 4fold. Structural analysis indicates that the linker attachment sites on maltose binding protein are at a site that, upon maltose binding, harbors both the largest local Calpha distance changes and displays surface curvature changes. Maltose activation and zinc inhibition of RG13 are hypothesized to have opposite effects on productive relaxation of the TEM-1 beta3 linker region via steric and/or linker juxtapositioning mechanisms 720869 3.5.2.6 additional information investigation of the potential for increased recognition of an extended-spectrum cephalosporin by targeted sequence variation in TEM-1 713474 3.5.2.6 additional information lactamase CoCo-L1, enzyme containing transition metal ions other than Zn(2+), prepared and characterized by kinetic and spectroscopic studies 696320 3.5.2.6 additional information lactamase Cu-L1, Cu-containing analog of metallo-beta-lactamase L1. Enzyme containing transition metal ions other than Zn(2+), prepared and characterized by kinetic and spectroscopic studies 696320 3.5.2.6 additional information lactamase Ni-L1, Ni-containing analog of metallo-beta-lactamase L1. Enzyme containing transition metal ions other than Zn(2+), prepared and characterized by kinetic and spectroscopic studies 696320 3.5.2.6 additional information lactamase NiZn-L1, enzyme containing transition metal ions other than Zn(2+), prepared and characterized by kinetic and spectroscopic studies 696320 3.5.2.6 additional information lactamase ZnCo-L1, enzyme containing transition metal ions other than Zn(2+), prepared and characterized by kinetic and spectroscopic studies 696320 3.5.2.6 additional information lactamase ZnFe-L1, enzyme containing transition metal ions other than Zn(2+), prepared and characterized by kinetic and spectroscopic studies 696320 3.5.2.6 additional information lactamase ZnNi-L1, enzyme containing transition metal ions other than Zn(2+), prepared and characterized by kinetic and spectroscopic studies 696320 3.5.2.6 additional information lactamase ZnZn-L1, enzyme containing transition metal ions other than Zn(2+), prepared and characterized by kinetic and spectroscopic studies 696320 3.5.2.6 additional information large scale mutant screening, construction of four deletion mutations in a class A beta-lactamase PenA, each conferring an extended substrate spectrum. Single-amino-acid deletions T171del, I173del, and P174del and a two-amino-acid deletion, R165_T167delinsP, occurr in the omega loop, increasing the flexibility of the binding cavity. The four additional deletion mutations in PenA extend the substrate spectrum, in addition to the characterized E168del mutation. The mutations are potential future mutations conferring high-level ceftazidime resistance on isolates from clinical settings, compared with amino acid substitution mutations. MIC values of mutant enzymes for antibiotics ceftazidime, amoxicillin, amoxicillin-clavulanic acid, cefotaxime, ceftriaxone, cefepime, and meropenem, overview. None of the deletion mutations confer resistance to cefepime, a fourth-generation cephalosporin, or to meropenem, a carbapenem subgroup member, but the deletion mutations exhibit various profiles of resistance to expanded-spectrum cephalosporins 733117 3.5.2.6 additional information mutagenesis is performed to better understand the basis of the inhibitor-resistant phenotype in SHV, examination of the role of a second-shell residue, Asn276 711206 3.5.2.6 additional information no significant loss in thermal stability for the point mutants compared to the wild-type enzyme 757320 3.5.2.6 additional information overproduction of a metallo-beta-lactamase by a strong promoter causes high-level imipenem resistance in a strain KG2505, PAO1 derivative without an AmpC beta-lactamase and a Mex-AB-OprM efflux pump, derived from a clinical human isolate of Pseudomonas aeruginosa, overview 691824 3.5.2.6 additional information replacement, separately or simultaneously, three of the ESBL alpha helices with prototype amphiphatic helices from a catalog of secondary structure elements. Although the substitutes bear no sequence similarity to the originals and pertain to unrelated protein families, all the engineered ESBL variants fold in native like structures with in vitro and in vivo enzymic activity. The triple substituted variant resembles a primitive protein, with folding defects such as a strong tendency to oligomerization and very low stability. It mimics a non homologous recombinant abandoning the family sequence space while preserving fold 713476 3.5.2.6 additional information TEM-107 extended-spectrum beta-lactamase detected in a Klebsiella pneumoniae clinical isolate has a Gly238Ser substitution compared to the TEM-43 beta-lactamase 718592 3.5.2.6 additional information the amino acid substitutions N132G, R164A, R244A, and R276E explain the broad specificity of the enzyme, relatively low penicillinase activity, and resistance to clavulanic acid 663664 3.5.2.6 N116H/N220G mutant enzyme with a broader specificity than wild type CphA 684481 3.5.2.6 N116H/N220G site-directed mutant of CphA, generated and characterized 696094 3.5.2.6 N116H/N220G/K224Q site-directed mutant of CphA, generated and characterized 696094 3.5.2.6 N136D random mutagenesis 733117 3.5.2.6 N136K random mutagenesis 733117 3.5.2.6 N136T random mutagenesis 733117 3.5.2.6 N152A site-directed mutagenesis, 6300fold reduced kinetic efficiency compared to the wild-type enzyme -, 654608 3.5.2.6 N166A/170G kcat/KM for ampicillin is 725fold lower than wild-type value, kcat/KM for penicillin G is 850fold lower than wild-type value 712398 3.5.2.6 N170A kcat/KM for ampicillin is 17fold lower than wild-type value, kcat/KM for penicillin G is 6fold lower than wild-type value, kcat/KM for cephalexin is 10fold lower than wild-type value, kcat/KM for cephalothin is 5fold lower than wild-type value 712398 3.5.2.6 N170G very efficient at hydrolyzing substrates that contain a primary amine in the antibiotic R-group that would be close to the Asn170 side chain in the acyl-intermediate. The X-ray structure of the N170G enzyme indicates that the position of an active site water important for deacylation is altered compared with the wild-type enzyme. N170G TEM-1 hydrolyzes ampicillin efficiently because of substrate-assisted catalysis where the primary amine of the ampicillin R-group positions the hydrolytic water and allows for efficient deacylation. kcat/KM for ampicillin is 3.5fold lower than wild-type value, kcat/KM for penicillin G is 1.6fold lower than wild-type value, kcat/KM for cephalexin is 1.7fold lower than wild-type value, kcat/KM for cephalothin is 40fold lower than wild-type value 712398 3.5.2.6 N170H random mutagenesis 733117 3.5.2.6 N170K random mutagenesis 733117 3.5.2.6 N170Y random mutagenesis 733117 3.5.2.6 N220G kinetic parameters of the wild-type and N220G mutant enzymes are not significantly different 666038 3.5.2.6 N276D reduced susceptibility to ampicillin/clavulanate while maintaining high-level resistance to ampicillin. Slightly diminished kcat/Km for all substrates tested. 5-fold increase in Ki for clavulanate and a 40% reduction in kinact/KI 711206 3.5.2.6 P174del random mutagenesis 733117 3.5.2.6 P174L random mutagenesis 733117 3.5.2.6 P174S random mutagenesis 733117 3.5.2.6 P226A site-directed mutagenesis, the mutant has 92% reduced activity compared to wild-type 757320 3.5.2.6 P252A site-directed mutagenesis, the mutant has 85% reduced activity compared to wild-type 757320 3.5.2.6 P28A naturally occuring genetic variation, the P28A substitution occurs in the predicted N-terminal periplasmic signal peptide 734041 3.5.2.6 P51L thermal stability is greatly decreased, mutant enzyme loses activity against cefotaxime and exhibits a reduced catalytic efficiency with penicillins and aztreonam, no inhibition by beta-odopenicillanate 663648 3.5.2.6 R163S random mutagenesis 733117 3.5.2.6 R164C random mutagenesis 733117 3.5.2.6 R164H random mutagenesis 733117 3.5.2.6 R164L random mutagenesis 733117 3.5.2.6 R164N activity unchanged or enhanced -, 209346 3.5.2.6 R164S activity unchanged or enhanced -, 209346 3.5.2.6 R164S side directed mutagenesis -, 695638 3.5.2.6 R234K site-directed replacement mutagenesis, about 4fold reduced catalytic efficiency compared to the wild-type enzyme 654597 3.5.2.6 R274N/R276N sitting-drop vapour-diffusion technique, surface-modified Toho-1 variant does not form merohedrally twinned crystals. Crystals diffract to a significantly higher resolution (0.97 A) than the wild-type crystals (1.65 A) 710730 3.5.2.6 R276C site-directed mutagenesis, the MICs of cefotaxime are clearly lower, clearly reduced catalytic efficiency towards cefotaxime. Investigation of the role of Arg276 in cefotaxime hydrolysis 698515 3.5.2.6 R276G site-directed mutagenesis, the MICs of cefotaxime are clearly lower, clearly reduced catalytic efficiency towards cefotaxime. Investigation of the role of Arg276 in cefotaxime hydrolysis 698515 3.5.2.6 R276H site-directed mutagenesis, investigation of the role of Arg276 in cefotaxime hydrolysis 698515 3.5.2.6 R276N site-directed mutagenesis, investigation of the role of Arg276 in cefotaxime hydrolysis 698515 3.5.2.6 R276S site-directed mutagenesis, the MICs of cefotaxime are clearly lower, clearly reduced catalytic efficiency towards cefotaxime. Investigation of the role of Arg276 in cefotaxime hydrolysis 698515 3.5.2.6 R276W site-directed mutagenesis, the MICs of cefotaxime are clearly lower, clearly reduced catalytic efficiency towards cefotaxime. Investigation of the role of Arg276 in cefotaxime hydrolysis 698515 3.5.2.6 R61H/E64H/43H circularly permuted enzyme, created by rational design. Mutant shows little regulation upon metal ion binding except for a weak activation with Zn2+ 720961 3.5.2.6 S104P mutant enzyme shows no beta-lactam hydrolytic activity 663653 3.5.2.6 S130G mutant resistant to tazobactam, sulbactam, clavulanic acid, and 2'-glutaroxy penem sulfone 685183 3.5.2.6 S130G site-directed mutagenesis, resistant to inhibition by taxobactam in contrast to the wild-type enzyme 656217 3.5.2.6 S164E thermal stability is increased, mutant enzyme loses activity against ceftazidime 663648 3.5.2.6 S191A site-directed mutagenesis, mutant shows highly declined resistance to antibiotics compared to wild-type NDM-7 -, 756926 3.5.2.6 S213A site-directed mutagenesis, the mutation does not signifcantly affect resistance of the cells against antibiotics -, 756926 3.5.2.6 S287N the AmpC variants AmpC-A and AmpC-B2 harboring the S287N substitution are obtained by mutagenesis from cephalosporinases representative of the phylogenetic groups A and B2 of Escherichia coli. Their biochemical characterization reveals that the S287N replacement leads to an important increase in the catalytic efficiency toward extended-spectrum cephalosporins in the AmpC beta-lactamase of group A only 695641 3.5.2.6 spin-labeled ImiS ImiS* 698477 3.5.2.6 ST70TS mutant bacteria show no beta-lactamase activity 209368 3.5.2.6 T157A site-directed mutant of CphA, generated and characterized 696094 3.5.2.6 T171P random mutagenesis 733117 3.5.2.6 T237A the mutant enzyme exhibits elevated MICs for ampicillin, piperacillin, and the beta-lactam–beta-lactamase inhibitor combinations. The T237A mutant enzyme demonstrates a lower kcat/Km for imipenem, cephalothin, and cefotaxime. The T237A mutant enzyme shows increased Kis for clavulanic acid, sulbactam, and tazobactam 710890 3.5.2.6 T237S the mutant enzyme maintains MICs equivalent to those of the wild type against all of the beta-lactams tested, including carbapenems. The mutant enzyme displays substrate kinetics similar to those of the wild-type KPC-2 enzyme. The T237S mutant enzyme displays Kis similar to wilde-type enzyme 710890 3.5.2.6 V67A site-directed mutant of CphA, generated and characterized 696094 3.5.2.6 V67D site-directed mutant of CphA, generated and characterized 696094 3.5.2.6 V67I site-directed mutant of CphA, generated and characterized 696094 3.5.2.6 V67LFKHV site-directed mutant of CphA, generated and characterized 696094 3.5.2.6 V88L/M154L naturally occuring genetic variation 734041 3.5.2.6 W154F noncarboxylated enzymes which displays poor catalytic efficiencies and reduced stability when compared to the wild-type OXA-10 711200 3.5.2.6 W154G noncarboxylated enzymes which displays poor catalytic efficiencies and reduced stability when compared to the wild-type OXA-10 711200 3.5.2.6 W154H noncarboxylated enzymes which displays poor catalytic efficiencies and reduced stability when compared to the wild-type OXA-10 711200 3.5.2.6 W229A site-directed mutagenesis, the mutant has 98% reduced activity compared to wild-type 757320 3.5.2.6 W229F site-directed mutagenesis, the mutant has 84% reduced activity compared to wild-type 757320 3.5.2.6 W229Y site-directed mutagenesis, the mutant has 82% reduced activity compared to wild-type 757320 3.5.2.6 W290F activity and spectroscopic properties of the mutant enzyme does not differ significantly from those of the wild type, indicating that the mutation has only a very limited effect on the structure of the protein. The stability of the folded protein is reduced, however, by 5-10 kJ mol-1 relative to that of the molten globule intermediate (H), but the values of the folding rate constants are unchanged, suggesting that Trp290 becomes organized in its native like environment only after the rate-limiting step, i.e., the C-terminal region of the enzyme folds very late -, 696228 3.5.2.6 Y194F site-directed mutagenesis, the mutant shows 62% reduced activity compared to the wild-type enzyme -, 758284 3.5.2.6 Y218F substitution may be responsible for the reduced catalytic efficiency against certain cephalosporins, including ceftazidime and cefepime 695635