• N N Chopra

      Articles written in Proceedings – Section B

    • Aminoacid deamination by thermophilic bacteria—Part I

      N N Chopra

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    • Aminoacid deamination by thermophilic bacteria—Part II

      N N Chopra

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    • Carbohydrates and microbial proteinases

      N N Chopra

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    • Proteolytic enzymes of thermophilic bacteria—part I

      N N Chopra

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      The thermophilic bacteriaBacillus thermophilus, B. aerothermophilus andB. thermoacidurans produce powerful proteinases which can be detected in the culture filtrates.

      These proteinases resemble tryptases in their optimum hydrogenion requirements and hydrolyse gelatin and casein readily and albumins sparingly, unless the albumin has been previously denatured.

      In addition to the proteinases these thermophilic bacteria also produce a polypeptidase capable of hydrolysing peptone, but this enzyme appears in culture filtrates much later than the proteinases.

      Velocity of gelatin hydrolysis by these proteinases varies directly as the square root of time and percentage of hydrolysis varies directly with the enzyme concentration.

      Relationship of substrate concentration and rate of hydrolysis shows that in case of gelatin Michaelis and Menton’s equation is applicable and that an intermediate enzyme-substrate complex consisting of one molecule each of the enzyme and the substrate is probably formed before the substrate is hydrolysed.

    • Proteolytic enzymes of thermophilic bacteria—Part II

      N N Chopra

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      The thermophilic bacteriaBacillus thermophilus, B. aerothermophilus andB. thermoacidurans produce very active proteinases which appear to be endocellular in character and are found in culture filtrates only as a result of autolysis of the cells.

      Filtrates obtained from broth cultures containing calcium and magnesium salts are proteolytically more powerful than those obtained from cultures prepared with ordinary broth, but the effect of these metals is on the activity of the proteinases and not on the quantity of the enzyme produced.

      Unlike papainases the proteinases of the thermophilic bacteria are not affected by copper ions.

      Activity of the proteinases of thermophilic bacteria is suppressed by methylene blue and is prevented by iodine.

      Although peptone itself is not hydrolysed by the proteinases of thermophilic bacteria, yet it hinders the hydrolysis of gelatin. The evidence obtained tends to show that the effect of peptone is probably due to competition by peptone with the gelatin for attachment to the active centre of the enzyme molecule, or a centre very close to the active centre.

    • The nature of proteinases of thermophilic bacteria

      N N Chopra

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