http://nopr.niscair.res.in/handle/123456789/3637 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/3712 Title: Partial purification of chlorophyll degrading enzymes from Cavendish banana (Musa Cavendishi) <br/> <br/>Authors: Janave, Machhindra T; Sharma, Arun <br/> <br/>Abstract: Cavendish banana (Musa Cavendishi, subgroup AAA) remains green upon ripening at tropical temperature (25-30ºC), due to incomplete degradation of chlorophyll (Chl). Earlier, evidence for the existence of two distinct degradative pathways ─ chlorophyllase and chlorophyll oxidase pathways in these bananas was provided. Here, an attempt has been made to understand further the mechanism of inhibition of Chl degradation at different stages of ripening and detecting various enzyme activities by partial purification. Soluble and Triton-solubilized protein fractions obtained from peel acetone powder from green-unripe, green-ripe and yellow-ripe bananas efficiently degraded Chl a. About 2-fold increase in Chl hydrolyzing/oxidizing and magnesium-dechelatase activities was observed in ripe, as compared to green-unripe bananas. The electrophoretic pattern of the soluble and detergent-solubilized proteins from the three stages of ripening revealed that the latter fraction contained only three slow moving proteins, which were found to be glycoproteins, as revealed in PAS staining. The soluble enzyme fraction contained all other bands along with the above three bands, as observed in the Native-PAGE of DEAE-Sepharose purified fractions. Only soluble fraction from ‘green-ripe’ bananas, catalyzed formation of an unknown intermediate (retention time 8.6 min), which was formed by the action of Triton-solubilized enzyme fractions, obtained from ‘green-unripe’ and ‘yellow-ripe’ bananas. The enzyme responsible for the formation of this intermediate might be involved in the stay-green character and could be a component of Chl oxidase pathway. Partial purification of soluble protein fraction by DEAE-Sepharose showed the presence of chlorophyllase, magnesium-dechelatase, pheophorbide a oxygenase, red fluorescent catabolite reductase and Chl oxidase. Native PAGE of pooled fractions showed separation of proteins in different bands. Pooled fractions IV and VI showed the presence of a single major band, resulting in almost a homogenous preparation in a single step. Fraction IV catalyzed dechelation of Mg by Mg-dechelatase, while fraction VI catalyzed the formation of 13²-OH-Chl a by chlorophyll oxidase. Chlorophyll oxidase activity was stimulated by linolenic acid, indicating involvement of lipoxygenase in oxidative Chl degradation, thereby resulting in the formation of 13²-OH-Chl a as product. The results show the presence of various enzymes of chlorophyllase and chlorophyll oxidase pathways in soluble enzyme fraction. <br/> <br/>Page(s): 154-161 http://nopr.niscair.res.in/handle/123456789/3711 Title: Cloning, high-level expression and enzymatic properties of an intracellular serine protease from Bacillus sp. WRD-2 <br/> <br/>Authors: An, Sun-Young; Ok, Min; Kim, Ji-Youn; Jang, Moon-Sun; Cho, Young-Su; Choi, Yong-Lark; Kim, Cheorl-Ho; Lee, Young-Choon <br/> <br/>Abstract: A gene, isp-B, encoding an intracellular serine protease from a newly isolated Bacillus sp. WRD-2 was cloned and characterized. Nucleotide sequence analysis showed an open reading frame of 960 bp encoding a polypeptide comprised of 319 amino acids. The primary structure of the enzyme predicted the structural features characteristic of other intracellular serine proteases, including active sites, Ser, His and Asp, as well as no signal sequence. The predicted amino acid sequence showed more than 60% homology with the intracellular serine proteases from Bacillus species. When expressed in E. coli, the recombinant enzyme (rISP-B) was overproduced in the cytoplasm as soluble and active form. The purified enzyme was completely inhibited by phenylmethylsulfonyl fluoride, EDTA and antipain. The enzyme showed maximum activity at pH 8.0 and 45ºC. It was stable at pH from 7.5 to 11.0 and below 50ºC. <br/> <br/>Page(s): 141-147 http://nopr.niscair.res.in/handle/123456789/3710 Title: A study of aromatic hydrogen bonds of peptides with aromatic amino acid side-chains <br/> <br/>Authors: Nallini, A; Saraboji, K; Ponnuswamy, M N <br/> <br/>Abstract: The importance of hydrogen bonding studies lies in their structural, biological and medicinal applications. Non-conventional hydrogen bonds are weak, but are found to play an important role in biological molecules. In view of their importance a study of the aromatic hydrogen bonds in peptides with aromatic, amino acid side chains was carried out. The results indicate a reasonable probability for their occurrence, thereby enumerating their distinct features. <br/> <br/>Page(s): 184-187 http://nopr.niscair.res.in/handle/123456789/3709 Title: Biochemical characterization of a protein of albumin multigene family from serum of African catfish Clarias gariepinus Bloch <br/> <br/>Authors: Hasnain, Absar-ul; Ahmad, Riaz; Jabeen, Mumtaz; Khan, M Mushahid <br/> <br/>Abstract: A monomorphic albumin-like protein (CfSA) has been purified to homogeneity from the serum of African air-breathing catfish Clarias gariepinus Bloch. It has a molecular mass of ≅70 kD and shows a lesser electrophoretic mobility than human serum albumin (HSA) in native gels. The protein exhibits cross-reactivity against rabbit anti-HSA serum and shows considerable similarity with HSA in secondary structure, however, with some differences, as indicated by a slight shift in the peaks around 267 nm and 278 nm and the absence of shoulders at 276 and 283. A certain degree of similarity also exists between their tertiary structures with respect to aromatic asymmetric environment as indicated by far-UV CD spectra and the visible range CD spectra of bilirubin complexes. CfSA-bilirubin complex is mainly characterized by bisignate CD Cotton effects (CDCEs), having minima and maxima wavelengths at 406 and 486 nm, respectively and unlike HSA, it shows prominent additional maxima around 426 nm. Based on the number of sulfhydryls, CfSA is in the rank of advanced teleosts. The occurrence of albumin in C. gariepinus in relation to the evolutionary dichotomy of albumin and other members of its multigene family in class Pisces has been discussed. <br/> <br/>Page(s): 148-153