摘要:

In order to investigate the influence of the side‐chain length at position 3 of AM‐toxin I (cyclic tetradepsipeptide) on necrotic activity for apple leaf, two analogs of AM‐toxin I, [L‐2‐amino‐4‐(p‐methoxyphenyl)butanoic acid3]‐AM‐toxin I and [L‐2‐amino‐6‐(p‐methoxyphenyl)hexanoic acid3]‐AM‐toxin I, were synthesized by the conventional method. Spectra of1H‐n.m.r., u.v. and CD of the analogs were similar to those of natural or synthetic AM‐toxin I. The toxic activities of the analogs for apple leaf, however, were weak, indicating that the exact side‐chain length at position 3 must be one of the important factors for the induction of the activity. The interaction between AM‐toxin I and a pos

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb02744.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The dodecapeptide Ac‐Asp‐Lys‐Asp‐Gly‐Asn‐Gly‐Tyr‐Ile‐Ser‐Ala‐Ala‐Gaba‐OH is a modified calmodulin calcium binding domain III. The synthesis of the peptide by the solid phase method with a total protection scheme using PAM‐resin is reported. The purified compound has been characterized by1H n.m.r. spectroscopy, both in the presence and in the absence of calcium ions, at various pHs. No strong specific interaction seems to occur between the peptide and

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb02745.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The conformational basis for the differing opioid receptor selectivities of the cyclic cystine‐containing analogs, [D‐Cys2, D(or L)‐Cys5] enkephalinamide and the related penicillamine‐containing analogs, [D‐Pen2, D(or L)‐Cys5] enkephalinamide (penicillamine =β,β dimethylcysteine) was investigated by1H n.m.r. in aqueous solution. Comparison of chemical shift, temperature dependence of amide proton chemical shift, and coupling constant data suggests similar overall conformations for corresponding penicillamine‐ and cystine‐containing analogs. Differences in conformation and flexibility do appear in the carboxamide terminal region of the corresponding analogs, which may account for their selectivities for different classes of

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb02746.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Maltosyl and glucosaminyl derivatives of beta‐lactoglobulin (b‐LG) were analyzed for their physicochemical properties: reduced viscosity, ultraviolet difference spectra, intrinsic fluorescence, hydrophobicity and circular dichroism. The viscosity of these derivatives increased as the mass of the carbohydrates covalently linked to b‐LG increased. The ultraviolet difference spectra and the intrinsic fluorescence of these proteins revealed that the microenvironments of aromatic amino acid residues of b‐LG were increasingly exposed to the surface of the protein as the extent of modification increased; and the polarity of these residues also increased as modification increased. The hydrophobicities of M‐b‐LG derivatives decreased as the extent of modification increased while the hydrophobicities of G‐b‐LG derivatives were relatively unchanged. The circular dichroic analysis of these proteins indicated that the ordered secondary structures of the extensively modified derivatives of b‐LG were partially unfolded. Thus, the carbohydrates covalently linked to b‐LG altered many physiochemical properties. These physicochemical changes of b‐LG apparently resulted from an alteration of forces stabilizing the str

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb02747.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Putative proteinase inhibitors with the general structure Z. Arg. X.Phe.H (where X = Leu, Ile or Val) were prepared by solution synthesis using semicarbazone protection for the aldehyde function. These inhibitors showed strong activity towards chymotrypsin whereas the semicarbazones and dipeptides aldehydes showed considerably reduced activity. The structural requirements for inhibition would seem to mimic those of the natural chymotrypsin inhibitor chymostatin.

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb02748.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The enzyme lysolecithin:lysolecithin acyltransferase from rabbit lung has been found to have a relatively disordered conformation in solutions of high ionic strength. The protein exhibited an ordering of structure when salt was suppressed. This conformational change was concomitant with the loss of transacylase activity, the hydrolytic reaction remaining unchanged. Addition of NaCl caused a progressive disordering of structure with a parallel increase of transacylase activity.The acid denaturation of the protein, at low and high ionic strengths, showed that the ionization of groups with pK in the range 5.9–6.4 was essential for denaturation. The structure was stable at basic pH.The addition of lipids resulted in a non‐specific stabilization of the disordered conformation, in the same manner as the addition of NaCl.From these results, it is suggested that there are two conformations for this protein which differ in their ability to bind lysolecithin molecules in the enzyme deacylation step of the reaction. This hypothesis agrees with previously published properties of the enzyme, concerning aggregation with other proteins and kinetic data. From the amino acid composition and conformational properties, the authors suggest that this enzyme could be a peripheral membrane prot

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb02749.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The isolation and characterization of the initial intermediates formed during the irreversible acid denaturation of enzyme Ribonuclease A are described. The products obtained when RNase A is maintained in 0.5 M HCl at 30° for periods up to 20 h have been analyzed by ion‐exchange chromatography on Amberlite XE‐64. Four distinct components were found to elute earlier to RNase A; these have been designated RNase Aa2, Aa1c, Aa1b, and Aa1ain order of their elution. With the exception of RNase Aa2, the other components are nearly as active as RNase A. Polyacrylamide gel electrophoresis at near‐neutral pH indicated that RNase Aa1a, Aa1b, and Aa1care monodeamidated derivatives of RNase A; RNase Aa2contains, in addition, a small amount of a dideamidated component. RNase Aa2, which has 75% enzymic activity as compared to RNase A, consists of dideamidated and higher deamidated derivatives of RNase A. Except for differences in the proteolytic susceptibilities at an elevated temperature or acidic pH, the monodeamidated derivatives were found to have very nearly the same enzymic activity and the compact folded structure as the native enzyme. Fingerprint analyses of the tryptic peptides of monodeamidated derivatives have shown that the deamidations are restricted to an amide cluster in the region 67–74 of the polypeptide chain. The initial acid‐catalyzed deamidation occurs in and around the 65–72 disulfide loop giving rise to at least three distinct monodeamidated derivatives of RNase A without an appreciable change in the catalytic activity and conformation of the ribonuclease molecule. Significance of this specific deamidation occurring in highly acidic conditions, and the biological implications of the physiological deamidation reactions of proteins a

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb02750.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

A genetic variant of bovine proinsulin has been isolated using preparative reverse‐phase HPLC. The new proinsulin (bovine proinsulin II) differs from the known proinsulin (bovine proinsulin I) by a single amino acid residue at position C‐48 in the connecting peptide. The amino acid replacement is a leucine substitution for proline. The two proinsulins were found in a ratio of approximately 9:1, proinsulin I: proinsulin II. No chemical or biological differences were observed for the two proinsulins other than their different elution times on reverse‐phase

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb02751.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Four proteins have been isolated from wheat germ by methods analogous to those used to isolate HMG proteins from animal tissue. All four proteins have been shown to be chromosomal in origin. Although amino acid analyses show that three of these proteins have compositions similar to those of the mammalian HMG proteins,N‐terminal sequence analyses of these proteins show an absence of sequence homology with any of the mammalian HMG protein

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb02752.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Administration of testosterone enanthate to adult female rats lowered the level of hepatic prolactin receptor. Pubertal exposure of intact female rats to testosterone enanthate at the dose used did not affect the level of hepatic prolactin receptor in adults. However, the responsivity of such treated rats to testosterone challenge in adulthood was enhanced. Prepubertal ovariectomy of female rats lowered the level of hepatic prolactin receptor in adulthood. Exposure of the ovariectomized rats during puberty to mestranol (ethynylestradiol 3‐methyl ether) at the dose used did not restore the normal adult female rat's level of hepatic prolactin receptor. However, they did become more resistant to subsequent testosterone challenge in adulthood. Exposure of prepubescent ovariectomized rats to testosterone enanthate during puberty reduced the already diminished level of hepatic prolactin receptor further. In addition, these rats were rendered more responsive to testosterone challenge in adulthoo

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb02753.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY