Studies of Australian Ascidians. IV. Mollamide, a Cytotoxic Cyclic Heptapeptide From the Compound Ascidian Didemnum molle

1994 ◽  
Vol 47 (1) ◽  
pp. 61 ◽  
Author(s):  
AR Carroll ◽  
BF Bowden ◽  
JC Coll ◽  
DCR Hockless ◽  
BW Skelton ◽  
...  
Keyword(s):  
Amino Acids ◽  
Cyclic Peptide ◽  
Peptide Hydrolysis ◽  
One Dimensional ◽  
Crystallographic Study ◽  
Relative Stereochemistry ◽  
Cyclic Heptapeptide ◽  
Hydrolysis Of ◽  
Absolute Stereochemistry

A new cytotoxic cyclic heptapeptide, mollamide, has been isolated from the compound ascidian Didemnum molle. The structure of mollamide was initially deduced from one-dimensional and two-dimensional n.m.r . experiments at 300 MHz. The structure was confirmed by an X-ray crystallographic study, which showed the relative stereochemistry of the cyclic peptide. Hydrolysis of mollamide , and characterization of the amino acids by derivatization with Nα -(5-fluoro-2,4-dinitrophenyl)-L- alaninamide (FDAA; Marfey's reagent) gave the absolute stereochemistry; all constituent amino acids were the L-isomers. Cytotoxicity data are reported.

Substrate Preferences for Antiplasmin Cleaving Enzyme Hydrolysis of Peptides Derived from the α2-Antiplasmin Sequence.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1704-1704
Author(s):  
Kenneth W. Jackson ◽  
Victoria J. Christiansen ◽  
Kyung N. Lee ◽  
Christina F. Mason ◽  
Patrick A. McKee
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Enzyme Hydrolysis ◽  
Peptide Sequence ◽  
Peptide Hydrolysis ◽  
Cleavage Rate ◽  
Amino Terminal ◽  
Substrate Preferences ◽  
Polymorphic Position ◽  
Hydrolysis Of

Abstract Antiplasmin cleaving enzyme (APCE) is a proteinase that specifically, but slowly cleaves the Pro-Asn bond in long-form α2-antiplasmin (Met-α2AP) in human plasma. This slow cleavage produces a steady-state plasma mixture of Met-α2AP and an N-terminally shortened form of antiplasmin, Asn-α2AP. The Asn-α2AP form crosslinks to fibrin ~13-fold faster than Met-α2AP. A faster crosslink rate causes a greater number of antiplasmin molecules to become bound during fibrin formation, thereby enhancing resistance to fibrinolysis. Inhibition of plasma APCE may decrease the number of antiplasmin molecules crosslinked and result in clots that are more easily removed during fibrinolysis. Therefore, an inhibitor specific for APCE could potentially be used to regulate fibrinolysis. Human Met-α2AP exists in two polymorphic forms at position six in the mature sequence, with arginine predominant, and tryptophan accounting for a lesser percentage. We have determined the relative cleavage rates of synthetic peptides from a peptide library that span the cleavage site. The peptides contained all common amino acids except cysteine in the polymorphic position (P7 position). Arg was the optimal amino acid in this position with a relative cleavage rate ~5–10-fold faster than other amino acids except Lys, which was ~70% of the Arg rate. The P7 position Arg enhancement was also observed when Arg was in the P6 or P5 position, but no enhancement was observed when Arg was moved to positions P8, P4, P3 or P2. It was also determined that APCE is preferentially an endoproteinase rather than an aminodipeptidase, with a 10-fold greater rate of hydrolysis of the internal Pro-Asn bond in the Met-α2AP 1–17 peptide sequence MEPLGRQLTSGP-NQEQV over the Pro-Asn bond penultimate to the amino-terminal bond in the Met-α2AP 11–27 peptide sequence GP-NQEQVSPLTLLKLGN in peptide hydrolysis experiments. We conclude that APCE inhibitors designed with a positive charge placed upstream of the Pro-X scissile bond equivalent to five to seven amino acid residues may prove to be highly potent and specific. In addition, such inhibitors should also prove useful for blocking the activity of the closely related enzyme fibroblast activation protein. This work was supported by NIH grant HL072995.

Synthesis and characterization of syn–anti carboxylate-bridged one-dimensional copper(II) complexes with bis(2-pyridylmethyl)amino acids

Polyhedron ◽  
2004 ◽  
Vol 23 (6) ◽  
pp. 903-911 ◽  
Author(s):  
Ki-Young Choi ◽  
Yong-Man Jeon ◽  
Haiil Ryu ◽  
Je-Jik Oh ◽  
Hae-Hwan Lim ◽  
...  
Keyword(s):  
Amino Acids ◽  
Synthesis And Characterization ◽  
One Dimensional

Attempting to rewrite History: challenges with the analysis of histidine-phosphorylated peptides

2013 ◽  
Vol 41 (4) ◽  
pp. 1089-1095 ◽  
Author(s):  
Maria-Belen Gonzalez-Sanchez ◽  
Francesco Lanucara ◽  
Matthew Helm ◽  
Claire E. Eyers
Keyword(s):  
Amino Acids ◽  
Protein Function ◽  
Biologically Relevant ◽  
Phosphorylated Peptides ◽  
Higher Eukaryotes ◽  
Histidine Phosphorylation ◽  
Rapid Hydrolysis ◽  
Hydrolysis Of ◽  
Acid Labile

A significant number of proteins in both eukaryotes and prokaryotes are known to be post-translationally modified by the addition of phosphate, serving as a means of rapidly regulating protein function. Phosphorylation of the amino acids serine, threonine and tyrosine are the focus of the vast majority of studies aimed at elucidating the extent and roles of such modification, yet other amino acids, including histidine and aspartate, are also phosphorylated. Although histidine phosphorylation is known to play extensive roles in signalling in eukaryotes, plants and fungi, roles for phosphohistidine are poorly defined in higher eukaryotes. Characterization of histidine phosphorylation aimed at elucidating such information is problematic due to the acid-labile nature of the phosphoramidate bond, essential for many of its biological functions. Although MS-based strategies have proven extremely useful in the analysis of other types of phosphorylated peptides, the chromatographic procedures essential for such approaches promote rapid hydrolysis of phosphohistidine-containing peptides. Phosphate transfer to non-biologically relevant aspartate residues during MS analysis further complicates the scenario.

Isolation and partial characterization of a peptidase with trypsin-like activity from bovine adenohypophysis

1989 ◽  
Vol 54 (8) ◽  
pp. 2276-2286
Author(s):  
Tsezengijn Dash ◽  
Tomislav Barth ◽  
Jiřina Slaninová ◽  
Jana Barthová ◽  
Hana P. Mašková ◽  
...  
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Partial Characterization ◽  
Chromogenic Substrate ◽  
Fluorogenic Substrate ◽  
Basic Amino Acids ◽  
Optimum Ph ◽  
Reproducible Method ◽  
Hydrolysis Of

A reproducible method has been developed for the isolation of the adenohypophyseal enzyme with a trypsin-like activity. The enzyme is able to hydrolyze Nα-benzoyl-L-arginine-p-nitroanilide, a fluorogenic substrate CBzl-Arg-Arg-β-naphthyl amide and some peptides with one or two accumulated basic amino acids in the chain. The optimum pH for hydrolysis of the chromogenic substrate was within the range 6.0-7.0 (Km = 0.66 mmol l-1), in the case of the fluorogenic substrate the range was between 7.0 and 7.5 (Km = 1.2 μmol l-1). The enzyme is activated by cysteine and dithiothreitol and inhibited by SH-poisons. The molecular weight of the enzyme, determined by means of two independent methods, was approximately 25 kDA.

scholarly journals Characterization of Eight Novel Spiroleptosphols from Fusarium avenaceum

Molecules ◽  
2019 ◽  
Vol 24 (19) ◽  
pp. 3498 ◽  
Author(s):  
Klaus Ringsborg Westphal ◽  
Manuela Ilse Helga Werner ◽  
Katrine Amalie Hamborg Nielsen ◽  
Jens Laurids Sørensen ◽  
Valery Andrushchenko ◽  
...  
Keyword(s):  
Mass Spectrometric ◽  
Vibrational Circular Dichroism ◽  
Fusarium Avenaceum ◽  
Chemical Analyses ◽  
Mass Spectrometric Data ◽  
Spectrometric Data ◽  
Relative Stereochemistry ◽  
Absolute Stereochemistry ◽  
Resolution Mass

Chemical analyses of Fusarium avenaceum grown on banana medium resulted in eight novel spiroleptosphols, T1, T2 and U–Z (1–8). The structures were elucidated by a combination of high-resolution mass spectrometric data and 1- and 2-D NMR experiments. The relative stereochemistry was assigned by 1H coupling and NOESY/ROESY experiments. Absolute stereochemistry established for 7 by vibrational circular dichroism was found analogous to that of the putative polyketide spiroleptosphol from Leptosphaeria doliolum.

Superficial or Membrane Digestion of Peptides in Dinitrophenol-Inhibited Rat Small Intestine

1979 ◽  
Vol 57 (2) ◽  
pp. 217-220 ◽  
Author(s):  
M. L. G. Gardner
Keyword(s):  
Amino Acids ◽  
Small Intestine ◽  
Free Amino ◽  
Rat Small Intestine ◽  
Peptide Hydrolysis ◽  
Brush Border Enzymes ◽  
Contact Digestion ◽  
Membrane Contact ◽  
Hydrolysis Of ◽  
Important Site

1. Hydrolysis of peptides has been measured in isolated rat small intestine perfused with a pancreatic digest of lactalbumin in the presence of 2,4-dinitrophenol. 2. Although transport of water and amino acids was severely inhibited by 2,4-dinitrophenol, peptide hydrolysis to free amino acids was apparently unimpaired. 3. Only a small fraction of the hydrolysis observed could be accounted for by leakage of enzymes into the lumen. 4. The results show that the brush-border enzymes proximal to the transport mechanism(s) can be an important site of hydrolysis of peptides to amino acids under conditions where the transport of unhydrolysed peptides is inhibited. The results are consistent with the concept of membrane (contact) digestion, although the significance of intracellular hydrolysis and of transmural transport of intact peptides is also discussed.

Improved purification and further characterization of Clostridium perfringens type A enterotoxin

1973 ◽  
Vol 19 (11) ◽  
pp. 1379-1382 ◽  
Author(s):  
A. H. W. Hauschild ◽  
R. Hilsheimer ◽  
W. G. Martin
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Clostridium Perfringens ◽  
Amino Acid Analysis ◽  
Sedimentation Coefficient ◽  
Type A ◽  
Sedimentation Equilibrium ◽  
Molecular Weights ◽  
Hydrolysis Of

The procedure for the purification of Clostridium perfringens type A enterotoxin was simplified, and the purity of the toxin was improved. Hydrolysis of the toxin by the p-toluenesulfonic acid procedure yielded 18 common amino acids. Among these, aspartic acid, serine, leucine, and glutamic acid were the predominant components. The sedimentation coefficient (s°20, w) was 2.8 Svedberg units. The molecular weights determined by the Archibald technique, sedimentation equilibrium, and amino acid analysis were 40 000, 36 000, and 33 000, respectively.

The nature of epidermidins, new antibiotics from staphylococci

1972 ◽  
Vol 18 (2) ◽  
pp. 121-125 ◽  
Author(s):  
Chun-yang Hsu ◽  
G. M. Wiseman
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Staphylococcus Epidermidis ◽  
Cyclic Peptide ◽  
Average Molecular Weight ◽  
Partial Hydrolysis ◽  
Amino Acid Residues ◽  
Peptide Fragments ◽  
New Antibiotics ◽  
Hydrolysis Of

New antibiotics have been isolated from Staphylococcus epidermidis strains 29297 and 36534. These agents are designated epidermidins A1, A2, B1, B2 and are peptides with an average molecular weight of 1200–1400 based on three independent methods of estimation. Each fraction contained 11 amino acid residues, eight of which were shared in common. The ratio of L- to D-amino acids was 7:4 for epidermidins A2 and B1, while that for epidermidins A1 and B2 was 5:6.The appearance of the same amino acids at the beginning and end of many of the peptide fragments obtained by partial hydrolysis of epidermidin A1 suggested that this antibiotic was a cyclic peptide. The absence of N- and C-terminal residues supported this finding. The amino acid sequence of epidermidin A1 was also tentatively deduced and may be written as follows: cyclo-lys-ala-asp-glu-ser-leu-thr-gly-val-gly-arg.

scholarly journals Isolation and characterization of sheep pepsin

1977 ◽  
Vol 161 (2) ◽  
pp. 389-398 ◽  
Author(s):  
P F Fox ◽  
J R Whitaker
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Composition ◽  
Ethyl Ester ◽  
Gel Filtration ◽  
Ph Optimum ◽  
Isolation And Characterization ◽  
Sepharose 4B ◽  
Hydrolysis Of

Sheep pepsin was isolated (approx. 120-fold purification) from aqueous abomasal homogenates by (1) pH fractionation, (2) chromatography on Sepharose 4B-poly-L-lysine columns and (3) gel filtration on Sephadex G-100. The enzyme had mol.wt. approx. 34000, N-terminal valine and C-terminal alanine. The amino acid composition of sheep pepsin was generally similar to that of pig and ox pepsins, with a very low content of basic residues and a high content of acidic and hydroxy-amino acids. The pH optimum for NN-dimethyl-casein and NN-dimethyl-haemoglobin as substrates was approx. 1.8. The Km and kcat. for NN-dimethyl-haemoglobin were 46micronM and 1100min-1 respectively, and for NN-dimethyl-casein the corresponding parameters were 50micronM and 420min-1. These values were generally similar to those for pig and ox pepsins. At the pH optimum of 4.6, the sheep pepsin was about 50% as active on benzyloxycarbonyl-L-histidyl-L-phenyl-alanyl-L-tryptophan ethyl ester as was pig pepsin. The pH optimum for the hydrolysis of N-acetyl-L-phenylalanyl-L-di-iodotyrosine by sheep, ox and pig pepsins was approx. 1.85.

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