摘要:

A lipophilic derivative of neocarzinostatin (NCS), an antitumor antibiotic, was prepared by reaction with a synthetic water‐soluble polymer, [(styrene)1˜3‐(maleic acid4˜7/anhydride1)]. The reaction was carried out at pH 8.6 for 3 h and aimed at modifying the two nonessential aming (of Ala‐1, ε‐amino of Lys‐20). The NCS‐polystyrene (SMANCS was a column of Sephadex G‐100 in 0.05 M ammonium bic and the main product was obtained as a single peak. The elemental and showed an increased C and a decreased N content. U.v. and i.r. absorption ectra for SMANCS showed the presence of styrene. SDS‐acrylamide gel electrophoresis at pH 8.5 and the decreased N content suggested a molecular high of about 25 000, Indicating the numbers of polymers conjugated to be six units, two of which were found attached to the two amino groups. SMANCS was solution in organic solvents, in contrast to NCS, and in water. SMANCS increased chemical and biological stability and appeared molicularin vitrob

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1979.tb01730.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The torsional potential functions Vt(φ) and Vt(ψ) around single bonds N–Cαand Cα‐C, which can be used in conformational studies of oligopeptides, polypeptides and proteins, have been derived, using crystal structure data of 22 globular proteins, fitting the observed distribution in the (φ, ψ)‐plane with the value of Vtot(φ, ψ), using the Boltzmann distribution. The averaged torsional potential functions, obtained from various amino acid residues inl‐configuration, are Vt(φ) = – 1.0 cos (φ + 60°); Vt(ψ) = – 0.5 cos (ψ + 60°) – 1.0 cos (2ψ + 30°) – 0.5 cos (3ψ + 30°).The dipeptide energy maps Vtot(φ, ψ) obtained using these functions, instead of the normally accepted torsional functions, were found to explain various observations, such as the absence of the left‐handed alpha helix and the C7conformation, and the relatively high density of points near the line ψ = 0°. These functions, derived from observational data on protein structures, will, it is hoped, explain various previously unexpl

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1979.tb01731.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Temperature‐activity and temperature‐stability relationships of malate dehydrogenases from eight thermophilic fungi were determined. Temperature optima for maximum activity of the enzymes varied between 50° and 60° and the Arrhenius plots were linear between 5° and 50°. The energies of activation ranged from 2.1 K cal/mol for the enzyme from Sporotrichum thermophile to 9.1 K cal/mol for that from Penicillium duponti. Heat inactivation kinetics at 50° revealed heat lability of the enzyme from most of the thermophilic fungi. The t1/2's (min) were<10 for the enzymes from P.duponti, S.thermophile and Thermoascus aurantiacus;30 for those from Mucor pusillus and H.insolens. Salts of Na+, K+and NH4+, and citrate protected the enzymes from H.lanuginosa, C.thermophile var. dissitum and M.pusillus against heat inac

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1979.tb01732.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Bovine growth hormone was chemically modified with picryl sulfonic acid, at pH 8.4 during 2 and 5 min of reaction. The N‐terminal residue provides the most reactive amino group followed by the amino groups of lysine 179 and lysines 143, 69, 111, 170 and 166 in decreasing order.These results agree with those obtained previously with equine growth hormone, except that residue 156 is not modified in bovine growth hormone, An important decrease in biological activity occurs between 2 and 5 min of reaction without sensible modification in the α‐helix content of the mole

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1979.tb01733.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The secondary structures of human somatotropin, human choriomammotropin, ovine and porcine prolactin, human, ovine and porcineβ‐lipotropin, human and ovine lutropin, human thyrotropin, human corticotropin, α‐melanotropin and humanβ‐melanotropin have been predicted by the method of Chou&Fasman. Predicted contents ofα‐helix andβ‐sheet do not correspond well with values estimated from circular dic

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1979.tb01734.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The n.m.r. spectrum of N‐methyl formamide oriented in a lyotropic liquid crystal solvent shows the presence of thecisas well as thetransforms. Analysis of the spectra due to both the species has been carried out. Possible non‐planar distortions at the nitrogen atom for thetransspecies have been computed using the derived dipolar couplings and the available structural d

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1979.tb01735.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The solid‐state conformational analysis of t‐AOC‐l‐Pro‐OH** has indicated that the molecules are not folded up to form an oxy‐C7peptide conformation, but rather that they are held together through intermolecular O‐H. 0 = C (urethane) hydrogen bonds. The tertiary amide bond is in the cis configuration. In solvents of high polarity strongly solvated species largely predominate. In cyclohexane solution non‐associated and associated (involving the carboxyl C = O as the proton acceptor) species are simultaneously present. Obviously, the extent of association increases with increasing solute concentration. The amount of the oxy‐C7form, if any, should be extremely small. It is also demonstrated that CD measurements alone can lead to an incorrect picture of the conformational preferences of amino acid derivatives and small pep

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1979.tb01736.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The synthesis of peptides containing blocks of arginyl residues is proposed through amidination of the corresponding ornithyl analogs. In order to test this strategy the ornithyl analog of the C‐terminal sequence 52–65 of galline was synthesized by the conventional method. The amidination reaction, performed on fragments of different length and ornithyl‐residue content, quantitatively converts ornithines into arginines. The strategy proposed may represent a powerful tool for the synthesis of protamines and other basic pro

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1979.tb01737.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The subunits of ovine lutropin prepared by acid dissociation and salt precipitation were characterized by end group analysis, tryptic peptide mapping, SDS gel electrophoresis and biological activity. No evidence of internal peptide cleavage was found in the α subunit. The subunits possessed low activity. The α and β subunits recombined effectively to generate a complex that had full receptor binding activity andin vitrobiological activity. The recombinants of subunits prepared by countercurrent distribution showed only 50% activity in both assays. The salt precipitation method α subunit could be completely reduced and reoxidized in the absence of denaturants. The reoxidized α subunit combines with the native β subunit generating full activity. However, this recombined hormone tends to lose activity with time, suggesting that the reoxidation may not fully restore the native structure of the reduced α subunit. The native lutropin α subunit effectively combined with follitropin β subunit generating complete follitropin

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1979.tb01738.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Electron microscopy of human ceruloplasmin (CP) molecules revealed a few distinctive types of particle images. Analysis of these images allows to propose a tentative model for CP: six “subunits” (which we call domains) not much different in size are arranged with 32 point group pseudosymmetry. The determination of the number of polypeptides arising at the spontaneous specific proteolytic fragmentation of CP and their molecular weights conform with this assumption. The electrophoretic studies of the CP samples preparated both with and without potent proteolytic inhibitor, PMSF, revealed that CP is a single‐chain protein with molecular weight of 130000. Isolated and stored without PMSF the polypeptide chain of CP undergoes specific proteolytic cleavage which results in the appearance of polypeptides with molecular weights of 16 000, 48 000, and 64 000. The latter two polypeptides degradate to about two‐ and three‐fold decreased molecular weights fragments, respectively. Therefore, the single polypeptide chain of CP contains at least five peptide bonds which are particularly susceptible to proteolytic attack and which connect six principal segments of the chain. The hydrolysis of these bonds results in liberation of the six fragments which were integrated in the enzymatically active glob

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1979.tb01739.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY