[show abstract][hide abstract] ABSTRACT: This study was undertaken to isolate and characterize the protease activity of human eye lens sample of mature and hyper mature cataract. Samples were collected just after surgery of the cataract lens and were stored at -20 degrees C. The total protein extract was isolated from 5 samples in each case (mature and hyper mature cataract) and clear supernatant obtained after centrifugation was used as an enzyme source. The optimum pH for the proteases of mature cataract was 7.5 while the proteases of hyper mature cataract were recorded for maximum activity at pH 5.5 and 7.5. The optimum temperature for both enzyme sources was 50 degrees C. Effect of different metal ions such as potassium, lead, silver, zinc and borate was studied. In each case protease activity was increased. Reducing agent e.g. beta mercaptoethanol also caused an increase in activity indicating the involvement of sulfhydryl groups. Protease activity was also located on agar plates.
Journal of Zhejiang University SCIENCE B 09/2007; 8(8):599-603. · 1.11 Impact Factor
[show abstract][hide abstract] ABSTRACT: Somatotropin, commonly known as growth hormone (GH) is a polypeptide chain containing about 190 amino acid residues, produced by the pituitary gland in mammals and is responsible for a number of anabolic processes. It has two disulphide bridges, with 4 alpha helices arranged in anti-parallel distinctive manner. GH molecule binds with two receptor molecules to exhibit its full biological activity. In this review, the information regarding characterization, structure and function is updated. A number of human growth hormone variants (naturally occurring and produced by recombinant DNA- technology) are visualised, and structure related functions are revealed. 1) The di-sulphide bridges are not essential for the biological activity of the molecule. The two chain variants of GH are able to show full biological activity. 2) The different domains of GH could be related to its functions 3) N-terminus of the molecule is involved in the galactopoietic activity of the molecule. 4) A single amino acid residue at a particular position could determine the magnitude of hormone receptor binding. 5) Role of Trp 86 is critical in packing of the apha helices bundles of the molecule. 6) Hydrophobic cores are essential for the stability of GH molecule 7) Salt bridges and hydrogen bonds are also important for the binding of the molecule with its receptors. 8) GH molecule has two binding sites for receptor molecules, Site I and Site II which are sterically coupled. The placental growth hormone has also been discussed and compared with the pituitary derived GH for its structure and function.
Current Protein and Peptide Science 07/2007; 8(3):283-92. · 2.33 Impact Factor