ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb03493.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The conformational properties of (Pro‐Phe‐Gly)nand (Phe‐Pro‐Gly)nwere investigated both in the solid state and in solution. In solid state X‐ray diffraction patterns seem to indicate that (Pro‐Phe‐Gly)nassumes a single chain triple helical structure. In solution, by circular dichroism studies, it was possible to show the existence of β‐bends in the presence of ethylene glycol. Similar studies carried out on (Phe‐Pro‐Gly)nshowed no collagen or polyproline 11–like structure in the solid state. In solution the β‐bend formation was apparent in all th

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb03494.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The association‐dissociation and denaturation behaviour of the major protein fraction,α‐globulin of sesame seed (Sesamum indicum L.), in acid and alkaline solutions in the ranges of pH 4.2–1.5 and pH 7–12 have been studied. The results of gel filtration, fluorescence and viscosity measurements indicate dissociation and denaturation of the protein up to pH ˜ 3. The difference spectrum in this region arises from a combination of dissociation, denaturation and charge effect on the chromophore. In still stronger acid solution, reassociation of the dissociated fraction takes place by hydrophobic interaction. In alkaline solution dissociation takes place around pH 8, and above pH 10 dissociation and denaturation proceed simultaneously as has been evidenced by sedimentation, fluorescence, spectral change, optical rotation and viscosity measurements. The phenolic group (pKInt= 10.6) in the protein is abnormal and denaturation in alkaline solution is irreversible. Above pH 11.5 further dissociation of the protein takes place. Characteristic pH values of transition from 10.6–10.8 indicate that the transition of the protein involves a single step in alkali

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb03495.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The thermophilic 6–phosphogluconate dehydrogenase from Bacillus stearo‐thermophilus was inhibited upon specific modification of the ‐SH group of cysteine residues by 7–chloro‐4–nitrobenzo‐2–oxa‐1, 3–diazole (NBD‐Cl) at pH 7.0. By using 20–100–fold molar excess of NBD‐CL the reaction occurs slowly at pH 7.0 as a first order process. Partial protection from inactivation was observed when the substrate 6–phosphogluconate or the coenzyme NADP was added to the reaction mixture. Complete inactivation was achieved upon modification of 1.9 of the six cystine residues per mole of enzyme, which corresponds to nearly one residue per enzyme subunit.Circular dichroism measurements suggest that the gross structure of the protein molecule is practically unchanged upon reaction of the enzyme with NBD‐Cl. Melting profile experiments revealed a single transition occurring at about 65d̀C. Analogously, the profile of intensity of the fluorescence emission at 520 nm of the enzyme‐bound S‐NBD groups versus temperature indicated a midpoint of transition near 65d̀C.Since this melting temperature corresponds closely to that observed with the native enzyme, these results would indicate that the molecular organizations of the native and modified enzyme are similar and stabilized by similar inte

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb03496.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Treatment of basic pancreatic trypsin inhibitor (BPTI, I) with cyanogen bromide smoothly yields the chain cleaved derivative II. The utility of the seco‐lactone (II) in the partial synthesis of protein analogues has been investigated. It is shown that the homoserine lactone ring is sufficiently reactive to combine directly with the radiolabelled synthetic peptide glycylglycylalanine t‐butyl ester in both aqueous and non‐aqueous solution, leading to a BPTI analogue which has been purified and characte

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb03497.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY