Inhibition enzyme thermal treatment

D-Lactate cytochrome c reductase is inhibited by p-mercuriphenyl sulfonate salts, metal chelators, and dicarboxylic acids such as oxalate and oxaloacetate (Table XVI) 312, 314, 315). According to Nygaard 314), salts (cations) inhibit at the acceptor site, and dicarboxylic acids at the substrate site. Cremona and Singer 315) have studied the inhibitions by metal chelators and by oxalate. They recognized two types of inhibition. One type of inhibition is that which is caused by EDTA or oxalate. This kind of inhibition is reversed immediately upon dilution of the enzyme-inhibitor mixture. The second is that which results from addition of o-phenanthroline. Enzyme preparations treated with o-phenanthroline bind 2 moles of the chelator per mole of Zn +. This complex is stable and inactive, and does not result in the release of Zn. The inactive o-phenanthroline-enzyme complex can be reactivated by dialysis, addition of divalent metal ions such as Zn +, Co +, Mn +, and Fe +, or by incubation at elevated temperatures (<45°) 312, 315-317). It has been shown that heat treatment does not involve the release of o-phenanthroline. The authors suggested that thermal reactivation of the o-phenan-... 

Jensenin P is a bacteriocin produced by P. jensenii B1264- which inhibits closely related propionibacteria and lactic acid bacteria. It was shown that jensenin P is a new anionic bacteriocin (Ratnam et al., 1998). Jensenin P is stable at lOOT for 45 min, at pH 2 to 10 for 225 min, and in 0.1 to 0.3M NaCl (pH 10) for 225 min (Barefoot et al., 1995). The resistance of jensenins to the extremes of pH and high temperature, their wide inhibitory spectrum allows to consider them as useful natural preservatives in thermal food processing. P. jensenii strain DFl was found (Miesher et al., 1998) to markedly inhibit other P. jensenii strains and to suppress 15 out of 24 yeasts and 3 out of 4 molds tested. From the culture broth of P. jensenii DFl an inhibitory protein substance, named SMI, was isolated and partially purified (Miesher et al., 1998). Crude propionicin SMI was sensitive to proteolytic enzymes and stable to incubation at 30°C (more than 14 days), cold storage (more than 6 months at 4 C) and heat treatment (15 min, 100 C). 

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