Question

Which mutation below is the least detrimental to the enzyme function? pH 8.0 Km (AM) 15 17 20 13 21 41 variant wild-type H57A H57L H57D H57E H57K HSOR D102N H57A, D102N H57D, D102N HSOK, D102N H57L, D102N S195A S195T H57A, D102N, S195A kbuffer (min) no enzyme kost (min-') 3200 0.054 0.075 0.78 0.69 0.83 0.017 1.3 0.17 0.18 0.41 0.13 0.079 0.011 0.038 67 keaK 210 0.0032 0.0037 0.06 0.033 0.020 0.00025 0.30 0.0019 0.0029 0.023 0.0031 0.0019 0.00052 0.00043 4.2 87 62 18 41 41 21 89 6.0 x 10-7

Answer 1

1) all mutant are detrimental as all mutation cause major changes in Kcat and somewhat in Km value too

2)mentioned mutation does not affect Km vslue so enzyme binding affinity doesnot change much but Kcat decreased a lot but Kcat value is greater to water as some of substrate can be cleaved and required nucleophile provide by side chain of same amino acids located at different position but efficiency decrease a lot.thsts why very slow reaction taking place.

Hope it's clear..thanks