Enzymes, listed

The microsomal fraction consists mainly of vesicles (microsomes) derived from the endoplasmic reticulum (smooth and rough). It contains cytochrome P450 and NADPH/cytochrome P450 reductase (collectively the microsomal monooxygenase system), carboxylesterases, A-esterases, epoxide hydrolases, glucuronyl transferases, and other enzymes that metabolize xenobiotics. The 105,000 g supernatant contains soluble enzymes such as glutathione-5-trans-ferases, sulfotransferases, and certain esterases. The 11,000 g supernatant contains all of the types of enzyme listed earlier. 

The major biochemical features of neutrophils are summarized in Table 52-8. Prominent feamres are active aerobic glycolysis, active pentose phosphate pathway, moderately active oxidative phosphorylation (because mitochondria are relatively sparse), and a high content of lysosomal enzymes. Many of the enzymes listed in Table 52-4 are also of importance in the oxidative metabolism of neutrophils (see below). Table 52-9 summarizes the functions of some proteins that are relatively unique to neutrophils. 

Relationships between reaction rate and temperature can thus be used to detect non-classical behaviour in enzymes. Non-classical values of the preexponential factor ratio (H D i 1) and difference in apparent activation energy (>5.4kJmoRi) have been the criteria used to demonstrate hydrogen tunnelling in the enzymes mentioned above. A major prediction from this static barrier (transition state theory-like) plot is that tunnelling becomes more prominent as the apparent activation energy decreases. This holds for the enzymes listed above, but the correlation breaks down for enzymes... 

D. Similar methods were used for modification of the enzymes listed in Table II as well as bovine hemoglobin (see Table III). The choice of conditions for the modification reactions (pH, temperature, etc.) was made mainly based on the properties/stability of each protein. Enzymatic activities were measured by previously reported methods (77,27-25). 

Protein phosphatase 1. Four subtypes of PP1, derived from three genes, are known. These enzymes, listed in Table 23-2, are highly homologous and exhibit similar substrate specificities therefore, they can be considered isoforms. However, the proteins exhibit very distinct patterns of distribution in the brain. PP1 dephosphorylates a wide array of substrate proteins. Its catalytic subunit can form complexes with over 50 regulatory subunits in a... 

Answer B. HPRT is required for activation of 6-mercaptopurine to its ribonucleotide and inhibition of purine synthesis. The other enzymes listed are not targets for this drug. 

The paperback atlas concludes with a series of schematic metabolic charts (pp. 407-419). These plates, which are not accompanied by explanatory text apart from a brief introduction on p.406, show simplified versions of the most important synthetic and degradative pathways. The charts are mainly intended for reference, but they can also be used to review previously learned material. The enzymes catalyzing the various reactions are only indicated by their EC numbers. Their names can be found in the systematically arranged and annotated enzyme list (pp. 420-430). 

In addition to the enzyme name, we also usually give its EC number. The annotated enzyme list (pp.420ff) includes all of the enzymes mentioned in this book, classified according to the Enzyme Catalog system. 

In addition, at each step the four-figure EC number (see p. 88) for the enzyme responsible for a reaction is given in italics. The enzyme name and its systematic classification in the system used by the Enzyme Catalogue are available in the following annotated enzyme list (pp. 420-430), in which all of the enzymes mentioned in this book are listed according to their EC number. The book s index is helpful when looking for a specific enzyme in the text. 

In this reaction, one molecule of ribulose-1,5-bisphosphate (metabolite 1) and one molecule of CO2 (metabolite 2) give rise to two molecules of 3-phosphoglycerate (metabolite 3). The enzyme responsible has the EC number 4.1.1.39. The annotated enzyme list shows that this refers to ribulose bisphosphate carboxylase ( rubisco for short). Rubisco belongs to enzyme class 4 (the lyases) and, within that group, to subclass 4.1 (the car-boxy-lyases). It contains copper as a cofactor ([Cu]). 

These copper ion-dependent enzymes [EC 1.10.3.1] (also referred to as diphenol oxidases, O-diphenolase, phe-nolases, polyphenol oxidases, or tyrosinases) catalyze the reaction of two catechol molecules with dioxygen to produce two 1,2-benzoquinone and two water. A variety of substituted catechols can act as substrates. Many of the enzymes listed under this classification also catalyze a monophenol monooxygenase activity [/.c., EC 1.14.18.1]. See also Monophenol Monooxygenase Tyrosine Monooxygenase... 

The presence of the following compound in the urine of a patient suggests a deficiency in which one of the enzymes listed below ... 

The Enzyme List maintained by the International Union of Biochemistry and Molecular Biology. 

Compare this number with known specific activity of the enzyme listed on the reagent bottle. 

A recurrent theme in many flavoprotein reactions is the probable involvement of FADH2 or the reduced form of FMN (FMNH2) as transient intermediates. Figure 10.10 illustrates a reasonable catalytic pathway for the first enzyme listed in table 10.2 this reaction shows the likely involvement of E FADH2 in each case. The mechanisms by which E FAD is reduced to E FADH2 by NADPH in the for-... 

The role of zinc in the enzymes listed in Table 12 is very often that of a strong Lewis acid, in which substrates are coordinated, polarized and hence activated. In other cases, zinc may play a regulatory, structural or template role. Zinc may also have a structural function in other biological molecules, for example in the unwinding and subsequent rewinding of the double-stranded polymers involved in replication and transcriptional processes. There is also evidence for a role for zinc in the stabilization of membranes and cell walls.463 The high concentrations of zinc in certain snake venoms reflect the presence in the venom of proteolytic enzymes and hemorrhagic toxins that all require zinc for activity.464... 

The enzymes listed in Table 23 (with the exception of nitrogenase) appear to contain a molybdenum-binding cofactor.995 These are interchangeable from enzyme to enzyme, where studied, and are probably identical. The factor is usually assayed by its ability to activate the... 

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