The mechanism of carbohydrase action. 3. The action pattern of β-amylase

Bailey, J. Martyn; Whelan, W. J.

doi:10.1042/bj0670540

Cited by 56 publications

(9 citation statements)

References 15 publications

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“…However, the pH values in the latter study only varied between pH 5.1 and 7.6 and this range may be too small to greatly affect amylase action pattern. Bailey & Whelan (1957) also found that, at optimum pH, the level of single attack action of β-amylase decreased with increasing temperature between 0 and 20 • C, was more or less constant between 20 and 60…”

Section: Amylases Action Patternsmentioning

confidence: 95%

“…Bailey & Whelan (1957) showed that with increasing pH, the action pattern of a β-amylase becomes more random. Likewise, Robyt & French (1967 reported that upon increasing the pH from the optimum pH 6.9 to 10.5 the action pattern of PPA changes from a multiple attack to a single attack action.…”

Section: Amylases Action Patternsmentioning

confidence: 99%

“…single chain action), since no intermediates of short chain length were detected during the action of β-amylase on amylose. Bailey & Whelan (1957) studied the action of β-amylase on maltohexaose, maltoheptaose and a synthetic amylose with a DP of 49. Their results indicated that the action pattern of β-amylase is intermediate between single-chain and multichain attack action (i.e.…”

Section: Amylases Action Patternsmentioning

confidence: 99%

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Amylase action pattern on starch polymers

2008

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Several decades ago, the first reports on differences in action pattern between amylases from different sources indicated that the starch polymers are not degraded in a completely random manner. We here give an overview of different action patterns of amylases on amylose and amylopectin, focusing on the so-called multiple attack action of the enzymes. Nowadays, the multiple attack action is generally an accepted concept to explain the differences in amylase action pattern. However, the pancreatic α-amylase remains one of the few enzymes known with a considerable level of multiple attack action. Despite some recent studies, the molecular mechanism of the multiple attack action is still largely unclear. Probably, the degree to which the active site architecture and binding properties allow both the reorganization (sliding) of the substrate in the active site and the stabilisation of the productive enzyme/substrate complex mainly determine the multiple attack action of amylases.

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Section: Amylases Action Patternsmentioning

confidence: 95%

Section: Amylases Action Patternsmentioning

confidence: 99%

Section: Amylases Action Patternsmentioning

confidence: 99%

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Amylase action pattern on starch polymers

2008

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“…The enzymes involved in the degradation of starch and their specific functions have been extensively reviewed (1,2,4,12,18,20,24,30). Of these enzymes, alpha and beta amylase are responsible for the bulk of the starch hydrolysis in the cereal endosperm.…”

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confidence: 99%

Site of Origin and Extent of Activity of Amylases in Maize Germination

Dure¹

1960

Plant Physiol.

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“…It might also be expected that polymerdegrading enzymes with a reaction mechanism intermediary between these two extremes would exist. I n a detailed study of the kinetic properties of 8-amylase) a plant enzyme that releases maltose residues from the non-reducing end of an amylose chain, such an intermediary action pattern was indeed observed in that a few maltose residues were removed at each effective enzyme-substrate encounter [5,9].In the present work, the mode of degradation of DNA and polydeoxynucleotides by mammalian DNase IV, an exonuclease that hydrolyzes doublestranded DNA from the 5'-ends [10-12], has been investigated. It is found that the enzyme does not attack its substrate in either a strictly random or in a single chain fashion.…”

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confidence: 99%

The Action Pattern of Mammalian Deoxyribonuclease IV

Lindahl¹

1971

European Journal of Biochemistry

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The mode of action of an exonuclease that probably is involved in DNA repair, mammalian DNase IV, has been studied. By kinetic measurements with both uniformly and terminally labeled polynucleotides it is shown that the enzyme breaks several adjacent phosphodiester bonds each time it binds to its substrate, but that the number of hydrolytic events is small compared to the degree of polymerization of the substrate. At 37" the enzyme releases 50-200 nucleotides in an exonucleolytic fashion a t each encounter with native DNA. The significance of these observations in relation to DNA repair in vivo is discussed.Enzymes that degrade linear polymers often act in a step-wise fashion by releasing one residue a t a time from one of the chain ends. An enzyme of this type is usually assumed to attack polymer chains in a random fashion, and to dissociate from its substrate after a single hydrolytic event. I n apparent contrast to such a mechanism of action, however, a number of exonucleases have recently been found to remain bound to their substrate during hydrolysis, so that one polynucleotide chain is completely degraded before the next one is attacked [l-41. An action pattern of this type has been referred to as single chain action I n the conventional Michaelis theory, an enzyme (E) and a substrate (S) are postulated to react in a reversible way to form a complex (ES), which then reacts to give products (P) and free enzymeIn the case of a polymer and an enzyme that remain associated and just move relative to each other during hydrolysis [5--81, the system is better represented by a modified expression I n this expression [5,8], the kinetic constants k,, Ll, and k, govern the rate of formation of an ES complex, its lifetime, and the rate of product formation, respectively. It further follows that the average number of hydrolytic events a t each encounter beUnusual Abbreviation. Poly[d(A-T)], an alternating double-stranded copolymer of deoxyadenylate and deoxythymidylate.All tritium-labeled polymers are labeled in the thymine residues.tween the enzyme and its polymer substrate is obtained directly from the ratio k, : k-l. Thus the two modes of action referred to above, random enzymatic attack at all available chain ends us. degradation of one complete polymer chain at a time, are not necessarily mutually exclusive ; they can instead be regarded as two extreme cases of the same type of reaction mechanism [5,8]. In the former case, the rate constant k-, should be larger than k,, while the reverse should be true in the latter case. It might also be expected that polymerdegrading enzymes with a reaction mechanism intermediary between these two extremes would exist. I n a detailed study of the kinetic properties of 8-amylase) a plant enzyme that releases maltose residues from the non-reducing end of an amylose chain, such an intermediary action pattern was indeed observed in that a few maltose residues were removed at each effective enzyme-substrate encounter [5,9].In the present work, the mode of degradation of DNA and polyde...

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The mechanism of carbohydrase action. 3. The action pattern of β-amylase

Cited by 56 publications

References 15 publications

Amylase action pattern on starch polymers

Amylase action pattern on starch polymers

Site of Origin and Extent of Activity of Amylases in Maize Germination

The Action Pattern of Mammalian Deoxyribonuclease IV

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