Site-directed mutagenesis studies

Q Zeng, ET Smith, DM Kurtz, RA Scott. Protein determinants of metal site reduction potentials. Site directed mutagenesis studies of Clostridium pasteurianum laibredoxin. Inorg Chim Acta 242 245-251, 1996. 

KAO Y c, ZHOU c, SHERMAN M, LAUGHTON 0 A, CHEN s (1998) Molecular basis of the inhibition of human aromatase (oestrogen synthetase) by flavone and isoflavone phytoestrogens a site-directed mutagenesis study. Environ Health Perspect. 106 85-92. 

Mayo KH, Ilyina E, Roongta V, et al. Heparin binding to platelet factor-4. An NMR and site-directed mutagenesis study arginine residues are crucial for binding. Biochem J 1995 312 357-65. 

While the ddNs and ANPs must be converted intracellularly to their 5 -triphosphates (ddNTPs) or diphosphate derivatives before they can interact as competitive inhibitors/alternate substrates with regard to the natural substrates (dNTPs), the NNRTIs do not need any metabolic conversion to interact, noncompetitively with respect to the dNTPs, at an allosteric, non-substrate binding site of the HIV-1 RT. Through the analysis of NNRTI-resistant mutants, combined with site-directed mutagenesis studies, it has become increasingly clear which amino acid residues are involved in the interaction of the NNRTIs with HIV-1 RT, and, since the conformation of the HIV-1 RT has been resolved at 3.0 A resolution [73], it is now possible to visualize the binding site of the NNRTIs [74],... 

L. K. Ozimek, S. A. van Hijum, G. A. van Koningsveld, M. J. van Der Maarel, G. H. van Geel-Schutten, and L. Dijkhuizen, Site-directed mutagenesis study of the three catalytic residues of the fructosyltransferases of Lactobacillus reuteri 121, FEBS Lett., 560 (2004) 131-133. 

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. 

His 118, Glu 146, His 128, His 142, Trpl, and His 14 as zinc binding ligands has been supported by a series of site-directed mutagenesis studies in which each of these residues was replaced with Ala each mutant bound only two zinc ions [35,64]. 

Identification of individual residues involved in substrate and inhibitor interactions has been accomplished through site-directed mutagenesis studies, either alone, or... 

Numerous site-directed mutagenesis studies have provided a conclusive picture for the molecular interactions between the receptor-activating biogenic amines (e.g. serotonin, epinephrine, dopamine) and their receptors [23-27] a highly conserved aspartate residue in transmembrane (TM) helix TM3 (Asp 3.32 according to the Ballosteros-Weinstein nomenclature) [28], conserved serine residues in TM5 (e.g. 

The mechanisms for the rednction of compounds I and II are less well nnderstood than the mechanism of compound I formation, although a number of suggestions have been presented in the literature (24). It is clear from site-directed mutagenesis studies that Arg38 and His42 are also important in the rednction steps, although their precise role has been difficnlt to define. A detailed mechanism for snbstrate oxidation by plant peroxidases has been proposed, based on data from the crystal... 

The proximal calcium binding site is coupled to the heme group by virtue of the fact that one of its ligands, Thrl71, is adjacent to the proximal histidine residue, Hisl70 (Fig. 4). The results of site-directed mutagenesis studies at this position are awaited with interest. An illustration of the importance of both calcium sites to the structure and function of HRP C is afforded by the need to incorporate calcium as a component of in vitro folding mixtures to obtain active recombinant enzyme from solubilized inclusion bodies (64). 

The contributions of hydrogen bond donors to catalysis can be estimated by site-directed mutagenesis studies in cases where the hydrogen bond donor is located in the amino acid side chain. Deletion of the main chain NH is only possible by substituting the amino acid with a proUne. In all cases, the effects of the substitution to key enzyme kinetic parameters, and K, should be checked. Typically, the oxyanion hole residues contribute only Uttle to the binding of substrate [19-21]. This is reflected in the values, which typically remain very similar... 

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