Enzyme amino dehydrogenase

The enzymes glutamate dehydrogenase, glutamine synthetase, and aminotransferases occupy central positions in amino acid biosynthesis. The combined effect of... 

The amino acid glutamate is deaminated in a reaction catalysed by the enzyme glutamate dehydrogenase, using either NAD+ or NADF as the oxidising agent, as follows ... 

The ammonia can then be utilised for amino acid synthesis in some or all of the microorganisms in the intestine, a process requiring the enzyme glutamate dehydrogenase to incorporate the ammonia into glutamate... 

Use the techniques outlined in the experimental procedure to explore two enzymes you will study in later experiments. Study the two enzymes malate dehydrogenase (Experiment 10) and tyrosinase (Experiment 5). View structures and look at amino acid sequences as you did for human a-lactalbumin. 

Several of the B vitamins function as coenzymes or as precursors of coenzymes some of these have been mentioned previously. Nicotinamide adenine dinucleotide (NAD) which, in conjunction with the enzyme alcohol dehydrogenase, oxidizes ethanol to ethanal (Section 15-6C), also is the oxidant in the citric acid cycle (Section 20-10B). The precursor to NAD is the B vitamin, niacin or nicotinic acid (Section 23-2). Riboflavin (vitamin B2) is a precursor of flavin adenine nucleotide FAD, a coenzyme in redox processes rather like NAD (Section 15-6C). Another example of a coenzyme is pyri-doxal (vitamin B6), mentioned in connection with the deamination and decarboxylation of amino acids (Section 25-5C). Yet another is coenzyme A (CoASH), which is essential for metabolism and biosynthesis (Sections 18-8F, 20-10B, and 30-5A). 

Amino acids NAD(P)H Pyridoxamine 5 -phosphate Pyruvate Amines Pyridoxal 5-phosphate dependent enzymes Dehydrogenases Transaminases Pyridoxal 5-phosphate dependent enzymes Amino acid decarboxylases... 

Different 2H-, 13C- and/or 15N isotopomers of L-serine, [(S)-2-amino-3-hydroxypro-panoic acid], 95, required for studies of aminoacid metabolism and for studies of peptide and protein structure and dynamics, have been biosynthesized stereoselectively84 using the serine-type methylotrophic bacterium, Methylobacteri extorquens AMI, which contains85 large amounts of the enzymes methanol dehydrogenase and hydroxymethyl-transferase (equation 39). 

Vitamins are required in the diet for groMh, maintenance, and reproduction. These qualities are shared by other nutrients, such as the amino adds and the minerals- Why are amino acids and minerals not called vitamins The vitamins share a family of characteristics. They are organic compounds required in the diet in only smaii amounts They are not catabolized to satisfy part of the energy requirement and are not used for structural purposes. Many vitamins are used as cofactors for enzymes. Pyruvate dehydrogenase is one striking example. This enzj me uses five cofactors, where four of these cofactors are derived from vitamins-... 

The enzyme methylamine dehydrogenase catalyzes the oxidation of amino-methane to formaldehyde according to the following equation ... 

For net removal of amino nitrogen, a second enzymatic reaction must take place that removes the amino group from Glu for disposal. The net removal of the amino nitrogen is accomplished by the mitochondrial enzyme glutamate dehydrogenase (GDH), which catalyzes the oxidative deamination of Glu to a-KG in a reaction that uses NAD+ as the electron acceptor. The enzyme can... 

Similarly, if one compares the form of the enzyme lactate dehydrogenase found in heart muscle to the type found in skeletal muscle, one can see small differences in amino acid composition. These differences in turn affect the reaction catalyzed by this enzyme, the conversion of pyruvate to lactate. The heart type has a high Kf, or a low afiinity for pyruvate, and the muscle type has a low K, or a high afiinily for pyruvate. This means that the pyruvate win be preferentially converted to lactate in the muscle but will be preferentially used for aerobic metabolism in the heart, rather than being converted to lactate. These conclusions are consistent with the known biology and metabolism of these two tissues. 

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