Zur Wirkungsweise der Hydrolasen

Myrbäck, Karl; Gripenberg, Jarl; Eskola, Salli; Laakso, Perttu V.; Laukkanen, Pentti

doi:10.3891/acta.chem.scand.01-0142

Cited by 20 publications

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“…Most frequently, bell-shaped v max -pH profiles in the pH range ca. 4.5-10.5 with the optimum pH around 7-8 have been reported for plant, bacterial and fungal ureases [1,5,13,16,17,23,[25][26][27][28][31][32][33]35,37,39] and analyzed in terms of two macroscopic pK a values, one on the acidic and the other on the basic side of the curve. Less frequently, three pK a s have been obtained by combining v max -pH curves noted in different buffers with the data derived from K M -pH curves [1,27].…”

Section: Significance Of Ph-variation Studiesmentioning

confidence: 99%

Jack bean (Canavalia ensiformis) urease. Probing acid–base groups of the active site by pH variation

Krajewska

Ciurli

2005

Plant Physiology and Biochemistry

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Section: Significance Of Ph-variation Studiesmentioning

confidence: 99%

Jack bean (Canavalia ensiformis) urease. Probing acid–base groups of the active site by pH variation

Krajewska

Ciurli

2005

Plant Physiology and Biochemistry

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“…Urease.-Myrback (232) has shown that the activity-pH curves of urease for different urea concentrations may be calculated from the M ichaelis-Menten theory, if it be assumed that a basic group in the enzyme molecule with Kb = about 5 X 10-8 is respon sible for the combination with urea (in a polar form). Deasy (233) states that high urea concentrations inhibit the enzyme in alkaline but not in acid solution.…”

Section: Experiments By Flock and Bollmanmentioning

confidence: 99%

Nonoxidative Nonproteolytic Enzymes

Myrbäck¹

1949

Annu. Rev. Biochem.

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It has been, more or less, a tacit assumption that enzymes constitute only a small part of the protein of the living cell.Virtanen has pointed out that from our present knowledge of the quantities of enzymes it seems justifiable to conclude that in microorganisms practically all protein is enzyme protein. There fore, the formation of an adaptive enzyme should correspond to a decrease in some other enzyme or enzymes, presumably of a related type. Lowering of the protein content of the cell by starvation should decrease primarily the amounts of adaptable (dispensable) enzymes, whereas the indispensable (constitutive) enzymes should maintain their activity. Virtanen & De Ley (1) have determined saccharase in E. coli which is, in this case, an adaptive enzyme, and catalase, a typically constitutive enzyme. By nitrogen starvation the protein content of the cells could be materially decreased. The saccharase content fell rapidly but catalase activity was only slightly affected. Investigations by Bucher & Kaspers (2) on the photochemical splitting of carbon monoxide hemoglobin may throw light on the action of the protein carrier on the prosthetic groups of enzymes. Not only radiation absorbed by the hemin splits off carbon monoxide, but also radiation absorbed by the protein. In the photo inactivation of urease the effect is the same, if the quanta are absorbed by a few tyrosine or tryptophane residues or by all amino acids. It is suggested that transmission of absorbed activation energy may be one of the causes of the chemical activation of prosthetic groups by the carriers. Attention is called to a paper by Veldstra (3) on the interaction of "ergones" and substrates. Rothen's experiments on "enzyme action at a distance" were mentioned in Vol. XVII of this Review. New experiments (4) have been published which are thought to exclude the possibility of diffusion of the enzyme through the protecting layers. Mettler, however, points out (5) that the antigen films are not of constant 1 This review covers approximately the period from December, 1947 to De cember, 1948. 59 Annu. Rev. Biochem. 1949.18:59-86. Downloaded from www.annualreviews.org Access provided by Technische Universiteit Eindhoven on 02/02/15. For personal use only. Quick links to online content Further ANNUAL REVIEWS

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The Mechanism of Action of Hydrolytic Enzymes

Lindley¹

1954

Advances in Enzymology - And Related Areas of Molecular Biology

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Zur Wirkungsweise der Hydrolasen

Cited by 20 publications

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Jack bean (Canavalia ensiformis) urease. Probing acid–base groups of the active site by pH variation

Jack bean (Canavalia ensiformis) urease. Probing acid–base groups of the active site by pH variation

Nonoxidative Nonproteolytic Enzymes

The Mechanism of Action of Hydrolytic Enzymes

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