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Ornithine decarboxylase half-life

It is an inhibitor of ornithine decarboxylase and is used as second line therapy for advanced CNS African trypanosomiasis. After oral or IV administration, peak plasma level is reached rapidly and elimination half life is approximately three hours. [Pg.359]

Tire synthesis of polyamines is tightly regulated. The PLP-dependent ornithine decarboxylase is present in very low concentrations226 and apparently has the shortest half-life ( 10 min) of any mammalian... [Pg.1381]

Protein molecules are synthesized rapidly (3-5 minutes) in vivo with a high degree of precision. The error level in the incorporation of specific amino acids into a growing polypeptidyl chain to give the primary sequence of a specific protein is estimated at about one error in every 104 to 105 amino acids incorporated. Unlike carbohydrates, every molecule of a given protein is identical in molecular weight, amino acid sequence, and secondary structure. When the proteins are released from the ribosomes they immediately are confronted with a hostile environment. Some proteins survive in the environment for only a few minutes while others last several years. For example, the half life of ornithine decarboxylase normally is about 11 minutes, while that of elastin is not readily measurable. [Pg.275]

The half-lives of proteins range over several orders of magnitude (Table 23.1). Ornithine decarboxylase, at approximately 11 minutes, has one of the shortest half-lives of any mammalian protein. This enzyme participates in the synthesis of polyamines, which are cellular cations essential for growth and differentiation. The life of hemoglobin, on the other hand, is limited only by the life of the red blood cell, and the lens protein, crystallin, by the life of the organism. [Pg.944]

Trade names Ornidyl Vaniqa (Women First) Indications Sleeping sickness, hypertrichosis Category Ornithine decarboxylase inhibitor Half-life IV 3-3.5 hours topical 8 hours... [Pg.203]

Elimination of unwanted proteins is just as important as synthesis of desirable proteins. The stability of cellular proteins varies over a wide range. Some unstable proteins have a half life of minutes, while others survive almost as long as the cell. A short half life simplifies the rapid control of protein concentration by synthesis or degradation. For example, in nondividing cells, ornithine decarboxylase is normally synthesized and degraded rapidly. When such cells are stimulated to proliferate, ornithine decarboxylase degradation slows down, resulting in a net increase in the concentration of ornithine decarboxylase protein. [Pg.764]

Synthesis of polyamines in the majority of cells is initiated by ornithine decarboxylase (ODC EC 4.1.1.17), which catalyses the conversion of ornithine to putrescine (Fig. 7.1) (4,13). In mammalian cells ODC undergoes rapid induction and has a short half-life. In the parasitic protozoa so far examined (T. b. brucei, P. falciparum, L. donovani and T. vaginalis), ODC has a long half-life as judged from the rate of decay of activity in the presence of cycloheximide (14-17). In African trypanosomes the slow turnover of ODC appears to be attributable to the absence of a 36 amino acid region (PEST sequence) on the COOH-terminal end (18,19). In mammalian cells, this is... [Pg.120]

A more dramatic difference is seen with ornithine decarboxylase (EC 4.1.1.17). This enzyme catcJyses the rale-limiting step in polyamine synthesis, and its activity in many tissues and organisms correlates well with the rate of DNA synthesis and cell proliferation. Its turnover is one of the most rapid of all enzymes, generally having a half-life of less than 20 min. Bullfield et al. (1988) have found a 20-fold higher activity in the skeletal muscle from the broiler strain compared with that in a layer strain of domestic fowl at one week of age. TTiis increased activity is almost certainly achieved by an increase in fcs with little change in fca-... [Pg.69]

Some proteins are subject to the C-terminal rule which predicts that proteins having a C-terminal stretch comprised predominantly of a PEST (Pro, Glu, Ser, and Thr) sequence motif are rapidly degraded (41). For example, ornithine decarboxylase containing the C-terminal PEST sequence has a half-life at least four times shorter than the same protein without the PEST motif (42). The PEST rule is subject to the polarity of the terminal residues nonpolar amino acids are destabilizing when placed at the five amino acid positions of the C terminus, whereas charged and polar residues are stabilizing (43). [Pg.14]

Ornithine decarboxylase is the only biosynthetic enzyme of putrescine in animals and has therefore been characterized extensively (Boucek and Lem-bach, 1977 Seely et al, 1982). This enzyme requires pyridoxal phosphate and its activity is induced in animals by partial hepatectomy (Raina et al, 1966), by hormones (Janne et al, 1978), and by carcinogenesis (O Brien et al, 1975). Its half-life is only 10 to 12 min, the shortest of any enzyme measured in eukaryotes (Russell and Snyder, 1968). This extremely short half-life may be related to an interesting regulatory mechanism for ODC (Heller et al, 1976). Addition of putrescine or of fetal calf serum leads to the production of a new 26,500-Da protein which is a noncompetitive inhibitor of ODC activity. This inhibitory protein has been called the ODC antizyme (Heller et al, 1976). [Pg.291]


See other pages where Ornithine decarboxylase half-life is mentioned: [Pg.1140]    [Pg.308]    [Pg.114]    [Pg.72]    [Pg.452]    [Pg.452]    [Pg.60]    [Pg.308]    [Pg.229]    [Pg.240]    [Pg.245]    [Pg.498]    [Pg.91]   
See also in sourсe #XX -- [ Pg.246 ]




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