Yamashita H, Nakatani H, Tonomura B
Department of Food Science and Technology, Faculty of Agriculture, Kyoto University, Japan.
Biochem Mol Biol Int. 1995 Jan;35(1):79-85.
The effect of chemical modification of lysine residues on the activity of porcine pancreatic alpha-amylase (PPA) was examined, using p-nitrophenyl-alpha-D-maltoside, p-nitrophenyl-alpha-D-maltotrioside, phenyl-alpha-D-maltoside and phenyl-alpha-D-maltotrioside as substrates. Chemical modification of PPA with trinitrobenzenesulfonic acid enhanced the kcat/Km values for p-nitrophenyl substrates, but not for phenyl substrates. Thus, this effect is substituent selective. Considering the productive binding modes of substrates to PPA, the p-nitro group of the substrate and the modified lysine residues of the enzyme would non-ionically interact with each other to stabilize the productive binding mode.
以对硝基苯基-α-D-麦芽糖苷、对硝基苯基-α-D-麦芽三糖苷、苯基-α-D-麦芽糖苷和苯基-α-D-麦芽三糖苷为底物，研究了赖氨酸残基的化学修饰对猪胰α-淀粉酶（PPA）活性的影响。用三硝基苯磺酸对PPA进行化学修饰提高了对硝基苯基底物的kcat/Km值，但对苯基底物没有影响。因此，这种效应具有取代基选择性。考虑到底物与PPA的有效结合模式，底物的对硝基基团与酶的修饰赖氨酸残基将通过非离子相互作用彼此稳定有效结合模式。
