摘要:

Two γ‐LPH variants have been isolated from ostrich pituitary glands using acid acetone extraction, salt fractionation, ion exchange and gel permeation chromatography and HPLC. The two fractions appeared homogeneous on PAG‐IEF (pI = 4.7) and both displayed an alanineN‐terminal residue. Amino acid composition and fragmentation data for these two peptides are in agreement with that expected for theN‐terminal 44 and 46 amino acid residues in ostrich β‐LPH, with corresponding molecular masses of 4911 and 5154 respectively. The molecular mass of the smaller variant was confirmed by means of sedimentation equilibrium centrifugation to be 4717. The two variants displayed lower lipolytic potencies than the corresponding peptides from ot

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb00958.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The synthesis of the four regioisomers of monothionated Leu‐enkephalins (Leu‐Enk) from previously reported protected precursors is described. The Tyr1‐thio analog was obtained as a 1:1 mixture of the L‐ and D‐Tyr diastereomers. The pure compounds were tested for opiate‐like activity by using the guinea‐pig ileum (GPI) and mouse vas deferens (MVD) preparations, by assessing analgesic effects following intra‐cerebroventricular administration and by examining their ability to displace [3H]‐D‐Ala2, D‐Leu5‐enkephalin (DADLE) and [3H]‐dihydromorphine from rat brain homogenates. The results demonstrate that depending on the backbone position of the thioamide function, activity can be decreased or increased. In the smooth muscle preparations as well as in the opiate binding tests, the activity of D, L‐Tyr1‐thio‐Leu‐Enk and Gly3‐thio‐Leu‐Enk was reduced. The activity of the latter analog was also diminished in the analgesia test. In all biological assays, Phe4‐thio‐Leu‐Enk was either equally or slightly less potent than the parent compound. However, introduction of the sulfur atom in position 2 of Leu‐Enk increased the potency of the compound in all assays, the MVD assay being the most sensitive. The results are interpreted in terms of the thioamide (amide) function in receptor recognition processes, the probable behavior of thiopeptides toward physiologically relevant peptidases and the structura

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb00959.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The susceptibility of the tyrosines of bovine thyrotropin (bTSH) and of its isolated α and β subunits to lactoperoxidase catalyzed iodination was examined as a probe of the reactivity of these residues. In isolated TSHα, tyrosines at positions 21, 41, 92 and 93 were labeled with radioactive iodine to a nearly equivalent extent while residue 30 did not incorporate iodine. In intact TSH tyrosine 41, as well as 30, was not modified showing that, upon association with β subunit, residue 41 becomes substantially less reactive. The other three tyrosines of the α subunit retained reactivity; residue 21 incorporated relatively more label than residues 92 and 93. The pattern of reactivity of the TSHα tyrosines in intact TSH parallels previous studies on the α subunits of lutropin (LH) and human choriogonadotropin (hCG). Thus the different primary sequences of the β subunits do not influence environments around tyrosines at positions which are spaced throughout the α subunit structure. Most of the 11 tyrosine residues of TSHβ incorporate significant amounts of iodine. In intact TSH, β tyrosines 25, 37, and 119 are most readily iodinated and tyrosines 14, 25 and 37 are the most reactive in the isolated subunit. Of particular interest in intact TSH is that tyrosine 37 and to a lesser extent 61 are modified. These tyrosines are found in analogous and highly conserved domains in the β subunits of all glycoprotein hormones whose sequences have been determined, but in LH and hCG they can only be iodinated in isolated

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb00960.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The N‐A isomerization of bovine plasma albumin (BPA) (the intramolecular sulfhydryl‐disulfide exchange reaction) is not atwo‐statebut amulti‐state reactionas shown in the following equationN ± A1+ mH+± A2+ nH+±where N and A1are the N‐ and A(aged)‐forms, respectively. The N‐A isomerization was strongly suppressed by increasing the ionic strength, especially by divalent cations, such as Ca2+. The N‐A isomerization was completely suppressed in the presence of 20 mM sodium caprylate and 40 mM N‐acetyltryptophan. This suppression of the intramolecular sulfhydryl‐disulfide exchange reaction might be due to the reduction of the structu

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb00961.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Stereoisomers of specific substrates for SFP and ELP, Suc‐L‐Tyr‐L‐Leu‐L‐Val‐pNA and Suc‐L‐Ala‐L‐Tyr‐L‐Leu‐L‐Val‐pNA, were synthesized by the conventional solution method. Suc‐L‐Tyr‐D‐Leu‐D‐Val‐pNA was found to be an effective and specific inhibitor of SFP and ELP. Suc‐L‐Tyr‐L‐Leu‐L‐Val‐Pipe and Suc‐L‐Tyr‐D‐Leu‐D‐Val‐Pipe inhibited only SFP very slightly and showed no inhibitory effect on ELP. Both Dan‐L‐Tyr‐L‐Leu‐L‐Val

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb00962.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Derivatives of the tetraguanidinated bovine trypsin‐kallikrein inhibitor lacking up to four amino‐acid residues have been prepared by Edman degradation of the amino‐terminal Arg‐Pro‐Asp‐Phe sequence. Comparative studies on the native inhibitor, tetraguanidinated inhibitor, and truncated sequences demonstrated that none of the fourN‐terminal amino‐acid residues are essential for the regeneration of native structure and biological activity by air oxidation of the reduced molecule.However residues 2, 3, and 4, although to a different extent, are important for the protein stability and significantly affect the conformation of the tetraguanidinated inhibitor and the rate of the reactivation process.Removal of the terminal positive charge from Arg 1 by diazotization gave a fully active deaminated, tetraguanidinated inhibitor but the lack of the salt bridge interaction between the amino and the carboxyl terminus of the protein prevented the correct folding of the reduced molecule by air oxidation as shown by activity measurements and conformational studies.The stability constants and the standard free energies of binding of the complexes between trypsin and the different inhibitor derivatives have

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb00963.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

γ‐L‐Glutamyl derivatives and a β‐L‐aspartyl derivative of different amines (taurine, nortaurine,N‐methyltaurine, taurine amide, tauryl‐methylamine, tauryl‐piperidine, β‐alanine amide, orthanilic acid, 2‐aminoethanephosphonic acid, ethanolamine‐O‐sulfate and ethanolamine‐O‐phosphate) have been synthesized by mixed anhydride or active ester coupling method. One of the dipeptide analogues, γ‐L‐glutamyl‐(ethanolamine‐O‐sulfate) was prepared by esterification, too. Syntheses of α,γ‐L‐glutamyl‐bis‐taurine and of DL

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb00964.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

In a search for a probe which would report its proteolysis to thrombin, the human blood coagulation zymogen prothrombin was covalently labeled with fluorescein. Fluorescein isothiocyanate (FITC) and dichlorotriazinylamino‐fluorescein (DCTAF) both introduced˜1 molecule of dye, but labeling occurred at different locations, as FITC had no effect on clotting activity whereas DCTAF caused 95% inactivation. At pH 9.0 DCTAF, but not FITC, could induce labeling up to 4 mol/mol. All derivatives were activated normally by prothrombinase (the activating complex of Factor Xa, Factor V(a), Ca2+and phospholipids), as indicated by the pattern of bands on SDS gel electrophoresis and an unaltered yield of activity toward a chromogenic substrate for thrombin. Upon undergoing this limited proteolysis, the most heavily labeled derivative showed a 40% increase in fluorescence of the fluorescein at 520 nm (Λex480 nm). In contrast, the fluorescence of lightly labeled forms was more intense but increased by only 0–5% upon activation. The data suggest that the lower fluorescence of the most labeled form is due to an intramolecular quenching effect between the dye molecules on individual polypeptide chains that is partly relieved when activation o

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb00965.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Fast atom bombardment (FAB) mass spectrometry has revealed a very useful technique in obtaining the mass spectrum of ceruletide (formerly caerulein), a decapeptide with a tyrosyl‐O‐sulphate residue, and of its desulphated analog. Molecular weight value for ceruletide is obtained only in the negative ion mode, whereas for [Tyr4] ceruletide this information is obtained both in negative and in positive ion detection. Positive ion mass spectra show more extended fragmentation which allows the complete amino acids sequence to be checked. The lability of the sulphate group has been confirmed, examining other sulphated peptides by field desorption mass spectrome

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb00966.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Crystallographically observed secondary structures in globular proteins are divided into two categories based on calculated potential values for these structures. Type I secondary structures are those which have maximum potential in observed structural state. These type I structures consist of those amino acids which intrinsically prefer that structural state. On the other hand type II secondary structures have a calculated potential value which is not maximum for the observed state. Type II structures are composed of those amino acid residues which do not intrinsically prefer the observed state and thus seem to have been formed due to tertiary interactions. All the observed secondary structures have been identified as type I or type II in 31 different globular proteins considered. It is suggested that type II structures are formed at a latter stage of protein folding mainly due to favourable tertiary interactions.

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb00967.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY