Kinetic substrate

Shimidzu etal.111 studied the catalytic activity of poly (4(5)-vinylimidazole-co-acrylic add) 60 (PVIm AA) in hydrolyses of 3-acetoxy-N-trimethylanilinium iodide 61 (ANTI) and p-nitrophenylacetate 44 (PNPA). The hydrolyses of ANTI followed the Michaelis-Menten-type kinetics, and that of PNPA followed the second-order kinetics. Substrate-binding with the copolymer was strongest at an imidazole content of 30 mol%. The authors concluded that the carboxylic acid moiety not... 

Studies on enzyme kinetics, substrate specificity and synergism... 

The enzymatic processes involved in the formation of catecholamines have been characterized. The component enzymes in the pathway have been purified to homogeneity, which has allowed for detailed analysis of their kinetics, substrate specificity and cofactor requirements and forthe development of inhibitors (Fig. 12-l).TheircDNAs have been cloned, and studies with knockout mice clearly indicate the importance of these enzymes since their... 

In general, this first generation of abzymes obtained from TSAs behave like enzymes, present saturation kinetics, substrate specificity, a stereoselectivity and competitive inhibition phenomena. However the acceleration factors obtained, cat/ ncat> remain weak and are limited in theory by the ratio of the constant of... 

Johnson and Fierke Hammes have presented detailed accounts of how rapid reaction techniques allow one to analyze enzymic catalysis in terms of pre-steady-state events, single-turnover kinetics, substrate channeling, internal equilibria, and kinetic partitioning. See Chemical Kinetics Stopped-Flow Techniques... 

Kinetic substrate solution Prepare as for dNTP substrate solution above, but using dNTP duo solution instead of dNTP trio solution. 

Mix equal volumes of polymerase buffer and kinetic substrate solution (containing only two cold dNTPs) and dispense 10-pL aliquots into a four separate sets of microfuge tubes. (If required, mixture or aliquots may be stored frozen for later use.)... 

Jackson, VN. and Halestrap, A.P. (1996) The kinetics, substrate, and inhibitor specffidty of the monocarboxylate (lactate) transporter of rat liver cells determined using the fluorescent intracellular pH indicator, 2 7 -bis(carboxyethyl)-5(6)-carboxyfluorescein. The Journal of Biological Chemistry, 271, 861—868. 

Unfortunately, most enzymes do not obey simple Michaelis-Menten kinetics. Substrate and product inhibition, presence of more than one substrate and product, or coupled enzyme reactions in multi-enzyme systems require much more complicated rate equations. Gaseous or solid substrates or enzymes bound in immobilized cells need additional transport barriers to be taken into consideration. Instead of porous spherical particles, other geometries of catalyst particles can be apphed in stirred tanks, plug-flow reactors and others which need some modified treatment of diffusional restrictions and reaction technology. 

A summary of some recently discovered inactivators of E. coli PFL is presented in Table V. Consistent with these compounds acting as mechanism-based or active site-directed inhibitors is the observation of pseudo-first-order inactivation kinetics, substrate protection (by pyruvate or formate for inhibitors that are pyruvate or formate analogs, respectively), and isotope effects on the rates of inactivation by the deuterated analogs. The details of some of these studies, the proposed inactivation mechanisms, and the implications to the normal enzymic reaction are discussed below. 

Complexation in molecular cavity Rate enhancements—saturation kinetics Substrate selectivity Reaction selectivity Competitive inhibition... 

FIGURE 4.1 Representative hyperbolic plot indicative of a reaction following Michaelis-Menten kinetics. = substrate concentration necessary to achieve one-half maximum velocity. Vmax = maximum velocity. 

Youshko Ml, Moody H, Bukhanov A et al. (2004) Penicillin acylase-catalyzed synthesis of 13-lactam antibiotics in highly condensed aqueous systems beneficial impact of kinetic substrate supersaturation. Biotechnol Bioeng 85 323-329... 

Structure-function analysis of peptide synthetases includes classical enzyme studies with no link to structural data. These have been carried out with enzyme kinetics, substrate analogs, inhibition studies, and the isolation of intermediates and products. Engineering approaches have employed mostly fragment expression and site-directed mutagenesis. In addition, first experiments with chimeric structures have been performed-... 

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