1.1.1.315 alignment of Streptomyces hydrogenans 20beta-hydroxysteroid dehydrogenase with rat retinol dehydrogenase and cow 11-cis retinol dehydrogenase. Lysine64 of the rat enzyme is important in stabilizing binding of 2'-phosphate on NADP+ in two ways: lysine's positively charged side chain has a coulombic attraction to the 2'-phosphate and partially compensates for the negative charge of aspartic acid-38. Cow 11-cis retinol dehydrogenase has threonine61 at the position homologous to lysine64. Threonine61 does not have a stabilizing coulombic interaction with NADP+, nor can threonine61 counteract the repulsive interaction between NADP+ and aspartic acid37 in 11-cis retinol dehydrogenase 1.1.1.315 modeling of the amino acid sequence of human RDH5 into the known three-dimensional structure of 17-hydroxysteroid dehydrogenase, Protein Data Bank code 1bhs