2.7.7.62 D101G in vitro activity relative to wild-type: 71%, monomer/dimer ratio: 34/66 724319 2.7.7.62 D83G in vitro activity relative to wild-type: 100%, monomer/dimer ratio: 82/18 -, 724319 2.7.7.62 E18D in vitro activity relative to wild-type: 56%, monomer/dimer ratio: 40/60 724319 2.7.7.62 G153D crystal structure of mutant is determined at 2.8 A: The protein crystallizes in the hexagonal space group P31 with 4 chains in the asymmetric unit. Mutant shows reduced activity and is composed of a monomer. Results from isothermal titration calorimetry experiments show that MjCobYG153D has 10fold higher affinity for GTP than wild-type, but fails to bind the corrinoid substrate 724319 2.7.7.62 G153D in vitro activity relative to wild-type: 2%, monomer/dimer ratio: 54/46 724319 2.7.7.62 G153D residues R13 and K19 of the mutant directly coordinate the phosphate group of GTP in the X-ray structure. The X-ray structure of the CobYG153D:GTP complex is modeled as a homodimer -, 739433 2.7.7.62 G8D mutant non-functional, monomer/dimer ratio: 33/67 724319 2.7.7.62 H45A site-directed mutagenesis 644438 2.7.7.62 H45A/H46A site-directed mutagenesis 644438 2.7.7.62 H46A site-directed mutagenesis 644438 2.7.7.62 H46N site-directed mutagenesis 644438 2.7.7.62 I144D/F146D/Y163R monomer/dimer/aggregate ratio: 77/23/0. Specific activity (pmol/min/microgram): 156 (monomer), 49 (dimer) 724319 2.7.7.62 K19A in vitro activity relative to wild-type: 16%, monomer/dimer ratio: 36/64 -, 724319 2.7.7.62 L38D/K41D monomer/dimer/aggregate ratio: 53/25/22. Specific activity (pmol/min/microgram): 125 (monomer), 120 (dimer), 78 (aggregate) 724319 2.7.7.62 L38K/K41D monomer/dimer/aggregate ratio: 52/26/22. Specific activity (pmol/min/microgram): 124 (monomer), 119 (dimer), 85 (aggregate) 724319 2.7.7.62 N177R in vitro activity relative to wild-type: 5%, monomer/dimer ratio: not determined 724319 2.7.7.62 N179D in vitro activity relative to wild-type: 95%, monomer/dimer ratio: not determined 724319 2.7.7.62 P20A in vitro activity relative to wild-type: 93%, monomer/dimer ratio: 63/37 724319 2.7.7.62 P54A in vitro activity relative to wild-type: 62%, monomer/dimer ratio: 50/50 724319 2.7.7.62 P94A in vitro activity relative to wild-type: 43%, monomer/dimer ratio: 52/48 724319 2.7.7.62 R13A in vitro activity relative to wild-type: 15%, monomer/dimer ratio: 14/86 724319 2.7.7.62 S100A in vitro activity relative to wild-type: 100%, monomer/dimer ratio: not determined -, 724319 2.7.7.62 S50A in vitro activity relative to wild-type: 100%, monomer/dimer ratio: not determined 724319 2.7.7.62 T180A in vitro activity relative to wild-type: 73%, monomer/dimer ratio: not determined -, 724319 2.7.7.62 T53S in vitro activity relative to wild-type: 84%, monomer/dimer ratio: 76/24 724319 2.7.7.62 T56A in vitro activity relative to wild-type: 102%, monomer/dimer ratio: not determined 724319 2.7.7.62 Y80F in vitro activity relative to wild-type: 65%, monomer/dimer ratio: 74/26 -, 724319