Carbamoyl Transferase Research Articles

Cloning and analysis of geldanamycin partial biosynthetic gene cluster of streptomyces hygroscopicus 17997

A geldanamycin (GDM)-producing strain, Streptomyces hygroscopicus 17997, was isolated from the soil of Yunnan, China, by the researchers of the Institute of Medicinal Biotechnology, CAMS & PUMC. GDM is an ansamycin antibiotic, which has the ability to bind with Hsp90 (heat shock protein 90) and alter its function. Hsp90 plays a key role in regulating the physiology of cells exposed to environmental stress and in maintaining the malignant phenotype of tumor cells. As an inhibitor of Hsp90, GDM possesses potent antitumoral and antiviral bioactivity, but the hypatotoxicity and poor solubility in water limit its clinical use. To accomplish the structural modification of GDM by genetic means, an attempt to obtain the biosynthetic gene cluster of GDM from S. hygroscopicus 17997 was made. In this study, a pair of primers was designed according to a conserved sequence of one of the possible post-PKS (polyketides synthase) modification genes, the carbamoyltransferase (CT) gene ( gdmN) in GDM biosynthesis. The 732-bp PCR product was obtained from the S. hygroscopicus 17997 genomic DNA. Through the colony-PCR Binary Search Method, using the CT gene primers, six positive cosmid clones, CT1-6, were identified from the S. hygroscopicus 17997 cosmid genomic library. The CT-4 positive cosmid was then sub-cloned and sequenced. Approximately 28.356 kb of foreign gene sequence from CT-4 cosmid and by further PCR extension reaction was obtained. According to BLAST analysis, this sequence contains 13 possible ORFs, and they are believed to be involved in GDM production. The obtained possible GDM biosynthetic gene cluster in S. hygroscopicus 17997 will facilitate the further functional analysis of the genes and the modification of the structure of GDM through combinatorial biosynthesis.

Ornithine carbamoyl transferase activity: Use of a bovine liver extract in quality control

To obtain a pure ornithine carbamoyltransferase for quality control in clinical chemistry, the authors compared human plasma and bovine liver ornithine carbamoyltransferase. The data show that the K M of both enzymes are similar (respectively 1.03 and 1.33 mmol when ornithine is used as substrate; 1.02 and 1.06 mmol with carbamyl phosphate). The following properties are shown to be equivalent: linearity of the enzymatic reaction, inhibition by higher substrate concentrations, and temperature denaturation. The similarities between the two enzymes indicate that bovine liver ornithine carbamoyltransferase can be used in clinical chemistry quality control.

A Review of Factors Affecting Blood Biochemistry in the Pig

SUMMARY Lack of information on the clinical biochemistry of the conventional pig compared with many other species is due, among other factors, to the present economic policy of culling or isolating unthrifty animal's without preliminary biochemical investigation, and the animal's intractability which makes blood and urine sampling difficult. This paper discusses the effects of some normal environmental factors such as age, sex, breed and particularly diet, as well as some disease conditions, on the levels of some organic serum components such as protein, urea, cholesterol, certain enzymes including alkaline phosphatase, glutamic pyruvic transaminase, glutamic oxaloacetic transaminase, glutamate and sorbitol dehydrogenases, arginase, carbamoyl transferase and lactate dehydrogenase, several of which are in current use in the diagnosis of liver disease and muscle dystrophy in other species. Bromsulphthalein clearance and urine analysis for common abnormalities are also discussed. It is concluded, on somewhat slender evidence, and taking into account the effects of age, diet, etc., that liver function can best be assessed routinely by S-GOT, OCT, possibly LDH and to a lesser degree by S-GPT, and kidney function by analysis of urine for abnormalities, and blood or serum for urea. Limited work indicates the possible value of BSP clearance for liver function, but intractability of the species renders this less useful as a routine test. Estimations of serum proteins and cholesterol do not appear to offer much useful information in assessing liver and kidney function. It is concluded that further basic studies must be carried out, more specifically on alkaline phosphatase, glutamate and sorbitol dehydrogenases in order to make it possible to recommend a larger battery of routine tests for liver function, and that estimations of serum urea, urinary protein and phenolsuiphonphthalein clearances should be investigated in connection with kidney function.

Electron microscopic demonstration of ornithine carbamoyltransferase in rat liver.

A method for electron microscopic demonstration of ornithine carbamoyltransferase (carbamyl phosphate: L ornithine carbamoyltransferase; E.C. 2.1.3.3) is described. The enzyme determination is based on precipitating the released orthophosphate with lead ions. Ornithine carbamoyl transferase activity is located in the mitochondrial matrix and in the cisternae of rough endoplasmic reticulum. The relation of citrulline synthesis in the urea cycle and ureidosuccinic acid synthesis competing for carbamoylphosphate is discussed.

Periodic increases in enzyme activity in synchronized cultures of Chlamydomonas reinhardtii

During synchronized growth of Chlamydomonas reinhardtii on a 12-h light-12-h dark cycle, net protein synthesis occurs approximately linearly in the light period but no appreciable increase is observed during the dark period of growth. Increases in activity of alanine dehydrogenase ( l-alanine:NAD oxidoreductase, EC 1.4.1.1), glutamate dehydrogenase ( l-glutamate:NAD(P) oxidoreductase, EC 1.4.1.3), phosphoenolpyruvate carboxylase (orthophosphate:oxaloacetate carboxylyase (phosphorylating), EC 4.1.1.31), aspartate carbamoyltransferase (carbamoylphosphate: l-aspartate carbamoyltransferase, EC 2.1.3.2) and ornithine carbamoyltransferase (carbamoylphosphate: l-ornithine carbamoyl transferase, EC 2.1.3.3) occur within characteristic periods of time during the life cycle of the cell. The activity of alanine dehydrogenase and aspartate carbamoyltransferase increases primarily in the light period, whereas the activity of the other three enzymes increases during the dark period of growth.