Site-directed mutagenesis activity effects

S182A <2> (<2> site-directed mutagenesis, no effect on enzyme activity [17]) [17]... 

DNA sequence indicated that AMDase contains four cysteine residues located at 101, 148, 171 and 188 from amino terminal (Eig. 9). At least one of these four is estimated to play an essential role in the decarboxylation. The most effective way to determine which Cys is responsible to enzyme activity will be site-directed mutagenesis. To determine which amino acid should be introduced in place of active Cys, its role was estimated as illustrated in Eig. 13. One possibility is that... 

Vuori, K., Pihlajaniemi, T., Myllyla, R. and Kivirikko, K.I. (1992) Site-directed mutagenesis of human protein disulfide isomerase - effect on the assembly, activity and endoplasmic-reticulum retention of human prolyl 4-hydroxylase in Spodoptera frugiperda insect cells. EMBO JoumalW, 4213-4217. 

The cytoplasmic domain of the P-subunit displays three distinct sub-domains (a) the juxtam-embrane domain , implicated in recognition/binding of intracellular substrate molecules (b) the tyrosine kinase domain, which (upon receptor activation) displays tyrosine kinase activity (c) the C-terminal domain, whose exact function is less clear, although site-directed mutagenesis studies implicate it promoting insulin s mitogenic effects. 

The carbon-carbon forming ability of aldolases has been limited in part by their narrow substrate utilization. Site-directed mutagenesis of various enzymes to alter their specificity has most often not produced the desired effect. Directed evolution approaches have furnished novel activities through multiple mutations of residues involved in recognition in no instance has a key catalytic residue been altered while activity is retained. Random mutagenesis resulted in a double mutant of E. coli 2-keto-3-deoxy-6-phosphogluconate (KDPG) aldolase with reduced but measurable enzyme activity and a synthetically useful substrate profile (Wymer, 2001). 

Daubner SC, Lauriano C, Haycock JW, Fitzpatrick PF (1992) Site-directed mutagenesis of serine 40 of rat tyrosine hydroxylase. Effects of dopamine and cAMP-dependent phosphorylation on enzyme activity. J Biol Chem 267 12639 16... 

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