Thymus gland, calf

Manson and Lampen243 reported that they obtained the phosphorolysis and arsenolysis of hypoxanthine desoxyriboside by enzyme preparations from calf-thymus gland and rat liver. An acid-stable phosphate ester was isolated as a product of phosphorolysis. Results to be outlined suggested that this ester was 2-desoxy-D-ribose 5-phosphate and evidence was obtained for its formation by a mutase type reaction from 2-desoxy-D-ribose 1-phosphate. This evidence was extended and reinforced when Manson and Lampen244 obtained indications for the formation of desoxy-D-ribose 1-phosphate during the phosphorolysis of thymidine. Consequently the conversions outlined may be depicted as shown. 

Thymosin fraction 5 (TF5) is a partially purified mixture of polypeptides prepared from calf thymus glands as starting material (Hooper et al., 1975). The crude thymus extract is purified by a heat step, acetone precipitation, and fractionation with ammonium sulfate. The 25%-50% ammonium sulfate precipitate is further subjected to ultrafiltration using an Amicon DC-2 hollow fiber system to yield fraction 5 that is lyophilized. Fraction 5 consists of 10 major and at least 30 minor polypeptides on analytical isoelectric gel focusing (Fig. 8), with molecular weights ranging from 1000 to 15,000, and is... 

Thymostimulin (TS) is an extract of calf thymus glands that has been partially purified by Falchetti et al. (1977) in Italy. Calf thymus tissue is first minced and extracted with ammonium acetate. This extract is then fractionated with ammonium sulfate precipitation. The 0-25% ammonium sulfate cut is further purified by ultrafiltration on an Amicon PM-10 membrane, desalted on Sephadex G-25, and gel filtered on Sephadex G-50. The biologically active preparation exhibits two predominant bands on polyacrylamide gels at pH 8.6. At the present time there have been no attempts to further define the constituents of this partially purified preparation. Although TS is similar to thymosin fraction 5 in its purification schema, a 0-25% ammonium sulfate precipitation step is used, whereas a 25-50% saturation fractionation cut is employed for the isolation of thymosin fraction 5. In addition, the purification procedure for TF5 includes an acetone precipitation step, whereas this procedure is not included in the preparation of TS. Thus, there... 

Yoneda, M., and F. J. BoUum. 1965. Deoxynucleotide-polymerizing enzymes of calf thymus gland. J. Biol. Chem., 240 3385-3391. 

Bertazzoni U, Mathelet M, Campagnari F (1972) Purification and properties of a polynucleotide ligase from calf thymus glands. Biochim Biophys Acta 287 404-414... 

Terminal deoxynucleotidyltransferase is a group of DNA polymerases which, unlike DNA- or RNA-directed polymerases, require neither DNA or RNA templates but catalyze linear condensation polymerization reactions. Terminal deoxynucleotidyltransferase is traditionally abbreviated as TdT, However, this book will break with the tradition and use TDTase to avoid any possible confusion with the dinucleotide TdT. TDTase, which was first isolated from the calf thymus gland, is found almost exclusively in the thymuses of a wide variety of mammals and birds and in certain lymphoid cells. TDTase from calf thymus is a heterodimer (44 kDa) and both subunits are derived from a single polypeptide precursor ( 60 kDa). 

The usual source of TDTase is the calf thymus gland. It contains 5-10 mg of TDTase per kg of fresh tissue. The enzyme is also found at high levels (100—200 U/10 cells) in certain leukemic lymphocytes (e.g., human leukemia Molt-4 and mouse thymoma PI 798) and at a detectable level in bone marrow. TDTase activity is not found in prokaryotes nor in unicellular eukaryotes. 

A second FTS RIA has been utilized to detect thymulin in extracts of pig and calf thymus (350-500 pg/g tissue) glands but not pig spleens (less than 2 pg/g tissue), which is consistent with a thymic origin for FTS. This assay has also been used to detect FTS in serum specimens. However, the assay is very cumbersome to perform since in order for it to be applicable to serum, samples must be filtered with an Amicon membrane, concentrated, and chromatographed on Sephadex G-25. Nevertheless, serum specimens obtained from thymectomized mice or pigs were found to be almost totally devoid (less than 2 pg/ml) of FTS immunoactivity and the greater than 25-fold decrease of serum FTS immunoactivity correlated with a 60-fold (from to i) decrease in FTS-like bioactivity as detected in the rosette-azathioprine assay. 

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