Some Aspects of Enzyme Reactions in Heterogeneous Systems

Ad, Mclaren; Packer, Lester

doi:10.1002/9780470122785.ch5

Cited by 78 publications

(35 citation statements)

References 195 publications

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“…Characteristically, the specific activity in the Michaelis–Menten case, which assumes substrate excess, is insensitive to [ E 0 ] ( s 0 ≫ e 0 , black). For comparison, the black hyperbola shows the specific activity of the classical mechanism in solution if the enzyme is in excess ( e 0 ≫ s 0 ), as advocated by McLaren and Packer [9] for colloidal substrates in suspension. However, for comparable parameter combinations this hyperbolic dependence on enzyme concentration does not resemble those found with a true adsorption model (blue curves), where we find different shapes depending on the surface areas a (for simplicity, we show the one‐way initial rate with Langmuirian adsorption, see Appendix B).…”

Section: Resultsmentioning

confidence: 99%

“…A similar breakthrough for surface-active enzymes is missing. There is no canonical kinetic description although specific models [3][4][5][6][7][8] and conceptual treatments [9][10][11] have been put forward. It is only consequent that even recent authoritative treatments on enzyme kinetics [12] shy away from discussing interfacial catalysis or do so only with a focus on special systems like membrane surfaces [13,Section 7.12].…”

Section: Introductionmentioning

confidence: 99%

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A generic rate law for surface‐active enzymes

Kartal

Ebenhöh

2013

FEBS Letters

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a b s t r a c tMany biochemical reactions are confined to interfaces, such as membranes or cell walls. Despite their importance, no canonical rate laws describing the kinetics of surface-active enzymes exist. Combining the approach chosen by Michaelis and Menten 100 years ago with concepts from surface chemical physics, we here present an approach to derive generic rate laws of enzymatic processes at surfaces. We illustrate this by a simple reversible conversion on a surface to stress key differences to the classical case in solution. The available area function, a concept from surface physics which enters the rate law, covers different models of adsorption and presents a unifying perspective on saturation effects and competition between enzymes. A remarkable implication is the direct dependence of the rate of a given enzyme on all other enzymatic species able to bind at the surface. The generic approach highlights general principles of the kinetics of surface-active enzymes and allows to build consistent mathematical models of more complex pathways involving reactions at interfaces.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A generic rate law for surface‐active enzymes

Kartal

Ebenhöh

2013

FEBS Letters

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“…Researchers reported that the enzyme-complexes mostly investigated are those attained by adsorption or interaction of enzyme molecules with pure clays, humus materials or humus-like compounds (Theng, 1979;Boyd and Mortland, 1990;Rao et al, 2000). Validamycin or other pesticides may combine with active site of soil enzyme or effect on substrate accessibility to the active site and caused chemical or conformational changes of enzymatic structure (McLaren and Packer, 1970;Nannipieri and Gianfreda, 1998). But these effect models were difficult to explain the effect of soil treated with validamycin on urease activity fluctuated between inhibition and promotion.…”

Section: Acid Phosphatasementioning

confidence: 98%

Effects of validamycin on some enzymatic activities in soil

Qian

Wang

et al. 2007

Environ Monit Assess

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There have been few investigations of the possible effects of validamycin on the enzymatic activities in soil. The objective of this present work was to study the short-term influence of enzymatic activity in validamycin treated soils. The results showed that high dose of validamycin introduced into soil had an significant effect on soil enzymatic activities, the degree of inhibition or promotion of enzymatic activities was not only related to the concentration of validamycin, but also to the remain time. Compared with the control (non treatment with validamycin), 240 ml.mg(-1) validamycin treatment caused a significant decrease (14%) of soil catalase activity; validamycin also inhibited urease activity to 67.3%, but subsequently, validamycin stimulated its activity higher than that of the control. Only the highest dose stimulated acid phophatase activities by 29.7%, and other concentration treatments had no effects on these enzymatic activities. The above results indicated that validamycin had effects on soil enzyme, but the effective time was short. It is also interesting to speculate that validamycin can be easily used by the soil microorganism as carbon source and energy.

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“…To describe the enzymatic adsorption, Freundlich and Langmuir sorption isotherms can be used. For gelatin, both isotherms were described in the literature 17,18 . For our data, the Freundlich sorption isotherm fit (Figure 1) was slightly superior to the Langmuir isotherm, because it was demonstrated that no upper limit of the approximate molar ratio of collagenase to collagen could be calculated 19 .…”

Section: Resultsmentioning

confidence: 63%

In vitro binding of matrix metalloproteinase‐2 (MMP‐2), MMP‐9, and bacterial collagenase on collagenous wound dressings

Metzmacher

Ruth

Abel

et al. 2007

Wound Repair Regeneration

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Chronic wounds are characterized by failure in wound-healing response and a delay in healing or nonclosure of the wounds. This results in a high effort in clinical treatment and/or home care. A major difference between acute wounds and chronic wounds is the imbalance of proteinase inhibitors and proteinase activity that regulates the degradation and regeneration of the extracellular matrix proteins. Collagen and collagen/oxidized regenerated cellulose dressings act as a competitive substrate for matrix metalloproteinase-2, matrix metalloproteinase-9, and bacterial collagenase and influence this imbalance positively. Both wound dressings, approved for chronic wound treatment, the bovine collagen type I sponge and the oxidized regenerated cellulose collagen sponge, did not differ significantly in their sorption profiles for all enzymes. In general, binding was enhanced with a longer incubation time. The density of the device and the accessible surface, which can be controlled by the manufacturing process, are the crucial factors for the efficiency of the wound dressing.

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Some Aspects of Enzyme Reactions in Heterogeneous Systems

Cited by 78 publications

References 195 publications

A generic rate law for surface‐active enzymes

A generic rate law for surface‐active enzymes

Effects of validamycin on some enzymatic activities in soil

In vitro binding of matrix metalloproteinase‐2 (MMP‐2), MMP‐9, and bacterial collagenase on collagenous wound dressings

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