Food Chemistry

2.2 General Remarks, Isolation and Nomenclature 97 rity can be tedious and is open to criticism. To- day, electrophoretic method ...

98 2 Enzymes lation are specified in addition to the name of the enzyme preparation; for example, “ascorbate ox- idase (E.C. 1.1 ...

2.3 Enzyme Cofactors 99 hand, during metabolism, the cosubstrate reacts with at least two enzymes. It transfers the hydro- gen o ...

100 2 Enzymes Table 2.4.Systematic classification of some enzymes of importance to food chemistry Class/subclass Enzyme EC- In t ...

2.3 Enzyme Cofactors 101 Table 2.4.Continued Class/subclass Enzyme EC- In text Number found under 3.1.4 Phosphoric diester Phosp ...

102 2 Enzymes 2.3.1.2 Adenosine Triphosphate The nucleotide adenosine triphosphate (ATP) is an energy-rich compound. Various gro ...

2.3 Enzyme Cofactors 103 2.3.2.2 Hemin................................................. Peroxidases from food of plant origin an ...

104 2 Enzymes (2.14) of the amino acid with formation of an α-keto acid. The reaction may also proceed through adecarboxylation( ...

2.3 Enzyme Cofactors 105 Ca^2 ⊕ ions are weaker Lewis acids than Mg^2 ⊕ions. Therefore, the replacement of Mg^2 ⊕ by Ca^2 ⊕may r ...

106 2 Enzymes Table 2.5.Redox potentials of Fe^3 +/Fe^2 +complex compounds at pH 7 (25◦C) as affected by the ligand Redox-System ...

2.4 Theory of Enzyme Catalysis 107 of several orders of magnitude. For example, glucose oxidase (Mr= 1. 5 · 105 ) and glucose (M ...

108 2 Enzymes with a number of proteinases and esterases alkylates the unusually reactive serine residue at the active site. Thu ...

2.4 Theory of Enzyme Catalysis 109 Fig. 2.9.A model for binding of a prochiral substrate (ethanol) by an enzyme 2.4.1.2.2 “Lock ...

110 2 Enzymes Fig. 2.11. A hypothesis for substrate binding by α-chymotrypsin, trypsin and elastase enzymes (accord- ing toShott ...

2.4 Theory of Enzyme Catalysis 111 effectiveness of chemical catalysts (examples in Table 2.2). The factors responsible for the ...

112 2 Enzymes Fig. 2.13.Example of a transition state analog inhibitorareaction of triosephosphate isomerase, TT: postulated tra ...

2.4 Theory of Enzyme Catalysis 113 Fig. 2.14.Influence of the steric effect on deacylation of two acyl-chymotrypsins (according ...

114 2 Enzymes tions simultaneously: (2.27) The imidazole ring (pK 2 = 6 .1) can cover the range of the pH optima of many enzymes ...

2.4 Theory of Enzyme Catalysis 115 only react with substrate by donating an electron pair (nucleophilic catalysis). Electrophili ...

116 2 Enzymes Fig. 2.18.Postulated mechanism for hydrolysis of amylose byβ-amylase by an SH-group on the carbon involved in the ...