Single peptide bond hydrolysis/resynthesis in squash inhibitors of serine proteinases. 1. Kinetics and thermodynamics of the interaction between squash inhibitors and bovine .beta.-trypsin

Biochemistry ◽  
1994 ◽  
Vol 33 (1) ◽  
pp. 200-207 ◽  
Author(s):  
Jacek Otlewski ◽  
Tomasz Zbyryt
Keyword(s):  
Peptide Bond ◽  
Serine Proteinases ◽  
Kinetics And Thermodynamics ◽  
Single Peptide

Single peptide bond hydrolysis/resynthesis in squash inhibitors of serine proteinases. 2. Limited proteolysis of Curcurbita maxima trypsin inhibitor I by pepsin

Biochemistry ◽  
1994 ◽  
Vol 33 (1) ◽  
pp. 208-213 ◽  
Author(s):  
Jacek Otlewski ◽  
Tomasz Zbyryt ◽  
Marek Dryjanski ◽  
Grzegorz Bulaj ◽  
Tadeusz Wilusz
Keyword(s):  
Trypsin Inhibitor ◽  
Limited Proteolysis ◽  
Peptide Bond ◽  
Serine Proteinases ◽  
Single Peptide

scholarly journals Tartrate-resistant acid phosphatase from human osteoclastomas is translated as a single polypeptide

1991 ◽  
Vol 277 (3) ◽  
pp. 631-634 ◽  
Author(s):  
A R Hayman ◽  
A J Dryden ◽  
T J Chambers ◽  
M J Warburton
Keyword(s):  
Acid Phosphatase ◽  
Peptide Bond ◽  
Northern Blotting ◽  
Tartrate Resistant Acid Phosphatase ◽  
Acid Phosphatases ◽  
Post Translational Modification ◽  
Subunit Protein ◽  
Single Polypeptide ◽  
Single Peptide

Tartrate-resistant acid phosphatases have been isolated from a number of sources. These enzymes consist of one subunit (Mr 30,000-40,000) or two dissimilar subunits (Mr 15,000-20,000). Previously we isolated the enzyme from human osteoclastomas, as a two-subunit protein. By Northern blotting and hybridization with radiolabelled oligonucleotides corresponding to the N-terminal sequences of the two subunits, we demonstrate here that the enzyme is transcribed as one mRNA which is translated in vitro to produce a single polypeptide of approx. Mr 33,000. Transcription as a single mRNA species is also the case in other tissues. These results suggest that the osteoclastoma enzyme undergoes post-translational modification in the form of cleavage of a single peptide bond to give a disulphide-bonded two-subunit protein.

scholarly journals Inactivation of human α1-proteinase inhibitor by thiol proteinases

1977 ◽  
Vol 163 (3) ◽  
pp. 639-641 ◽  
Author(s):  
D Johnson ◽  
J Travis
Keyword(s):  
Human Plasma ◽  
Active Site ◽  
Proteinase Inhibitor ◽  
Peptide Bond ◽  
Proteolytic Cleavage ◽  
Serine Proteinases ◽  
Phagocytic Cells ◽  
Thiol Proteinases

Human plasma alpha1 proteinase inhibitor is the body's principal modulator of serine proteinases (such as those released from phagocytic cells). Cysteine-active-site proteinases, which are not inhibited, have now been found to inactivate this important inhibitor by proteolytic cleavage of a scissile peptide bond. Papain carries out this inactivation catalytically, whereas cathepsin B1 acts stoicheiometrically. Thus thiol proteinases could easily disrupt the delicately regulated balance between serine proteinases and alpha1 proteinase inhibitor.

scholarly journals Albumin–Methotrexate Prodrug Analogues That Undergo Intracellular Reactivation Following Entrance into Cancerous Glioma Cells

Pharmaceutics ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 71
Author(s):  
Itzik Cooper ◽  
Michal Schnaider-Beeri ◽  
Mati Fridkin ◽  
Yoram Shechter
Keyword(s):  
Dihydrofolate Reductase ◽  
Glioma Cell ◽  
Glioma Cells ◽  
Peptide Bond ◽  
Glioma Cell Line ◽  
Native Structure ◽  
Free System ◽  
A Cell ◽  
Covalently Linked ◽  
Single Peptide

A family of monomodified bovine serum albumin (BSA) linked to methotrexate (MTX) through a variety of spacers was prepared. All analogues were found to be prodrugs having low MTX-inhibitory potencies toward dihydrofolate reductase in a cell-free system. The optimal conjugates regenerated their antiproliferative efficacies following entrance into cancerous glioma cell lines and were significantly superior to MTX in an insensitive glioma cell line. A BSA–MTX conjugate linked through a simple ethylene chain spacer, containing a single peptide bond located 8.7 Å distal to the protein back bone, and apart from the covalently linked MTX by about 12 Å, was most effective. The inclusion of an additional disulfide bond in the spacer neither enhanced nor reduced the killing potency of this analogue. Disrupting the native structure of the carrier protein in the conjugates significantly reduced their antiproliferative activity. In conclusion, we have engineered BSA–MTX prodrug analogues which undergo intracellular reactivation and facilitate antiproliferative activities following their entrance into glioma cells.

scholarly journals Protein inhibitors of serine proteinases.

1999 ◽  
Vol 46 (3) ◽  
pp. 531-565 ◽  
Author(s):  
J Otlewski ◽  
D Krowarsch ◽  
W Apostoluk
Keyword(s):  
Structural Changes ◽  
Proteinase Inhibitors ◽  
Peptide Bond ◽  
Serine Proteinases ◽  
Beta Sheet ◽  
Protein Inhibitors ◽  
Blood Sucking ◽  
Recognition Protein ◽  
Helical Proteins ◽  
Binding Loop

Serine proteinases and their natural protein inhibitors belong to the most intensively studied models of protein-protein recognition. Protein inhibitors do not form a single group but can be divided into about 20 different families. Global structures of proteins representing different inhibitor families are completely different and comprise alpha-helical proteins, beta-sheet proteins, alpha/beta-proteins and different folds of small disulfide-rich proteins. Three different types of inhibitors can be distinguished: canonical (standard mechanism) inhibitors, non-canonical inhibitors, and serpins. The canonical inhibitor binds to the enzyme through the exposed and convex binding loop, which is complementary to the active site of the enzyme. The mechanism of inhibition in this group is consistently very similar and resembles that of an ideal substrate. Non-canonical inhibitors, originating from blood sucking organisms, specifically block enzymes of the blood clotting cascade. The interaction is mediated through inhibitor N-terminus which binds to the proteinase forming a parallel beta-sheet. There are also extensive secondary interactions which provide an additional buried area and contribute significantly to the strength and specificity of recognition. Serpins are major proteinase inhibitors occurring in plasma. Similarly to canonical inhibitors, serpins interact with their target proteinases in a substrate-like manner. However, in the case of serpins, cleavage of a single peptide bond in a flexible and exposed binding loop leads to dramatic structural changes.

scholarly journals Azurocidin -- inactive serine proteinase homolog acting as a multifunctional inflammatory mediator.

2003 ◽  
Vol 50 (3) ◽  
pp. 743-752 ◽  
Author(s):  
Wiesław Watorek
Keyword(s):  
Inflammatory Mediator ◽  
Serine Proteinase ◽  
Peptide Bond ◽  
Catalytic Triad ◽  
Antimicrobial Protein ◽  
Gram Negative Bacteria ◽  
Serine Proteinases ◽  
Heparin Binding ◽  
Heparin Binding Protein ◽  
Cleave Peptide Bond

Azurocidin, also known as cationic antimicrobial protein 37 kDa (CAP37) or heparin-binding protein (HBP) is an inactive homolog of serine proteinases residing in granulocytes. The ability to cleave peptide bond was lost due to replacement of two of the three residues from the conserved catalytic triad characteristic for serine proteinases. Azurocidin has a broad spectrum of antimicrobial activity, mainly against Gram-negative bacteria. It is also recognized as a multifunctional inflammatory mediator for its contracting effects on endothelial cells causing an increase of vascular permeability, capacity to bind endotoxin and ability to attract monocytes to inflammation sites.

scholarly journals The interaction of α2-macroglobulin with proteinases. Characteristics and specificity of the reaction, and a hypothesis concerning its molecular mechanism

1973 ◽  
Vol 133 (4) ◽  
pp. 709-724 ◽  
Author(s):  
Alan J. Barrett ◽  
Phyllis M. Starkey
Keyword(s):  
Conformational Change ◽  
Molecular Mechanism ◽  
Active Site ◽  
Peptide Bond ◽  
Serine Proteinases ◽  
Equimolar Ratio ◽  
Binding Characteristics ◽  
Sensitive Region ◽  
Physiological Importance ◽  
Α2 Macroglobulin

1. α2-Macroglobulin is known to bind and inhibit a number of serine proteinases. We show that it binds thiol and carboxyl proteinases, and there is now reason to believe that α2-macroglobulin can bind essentially all proteinases. 2. Radiochemically labelled trypsin, chymotrypsin, cathepsin B1 and papain are bound by α2-macroglobulin in an approximately equimolar ratio. Equimolar binding was confirmed for trypsin by activesite titration. 3. Pretreatment of α2-macroglobulin with a saturating amount of one proteinase prevented the subsequent binding of another. We conclude that each molecule of α2-macroglobulin is able to react with one molecule of proteinase only. 4. α2-Macroglobulin did not react with exopeptidases, non-proteolytic hydrolases or inactive forms of endopeptidases. 5. The literature on binding and inhibition of proteinases by α2-macroglobulin is reviewed, and from consideration of this and our own work several general characteristics of the interaction can be discerned. 6. A model is proposed for the molecular mechanism of the interaction of α2-macroglobulin with proteinases. It is suggested that the enzyme cleaves a peptide bond in a sensitive region of the macroglobulin, and that this results in a conformational change in the α2-macroglobulin molecule that traps the enzyme irreversibly. Access of substrates to the active site of the enzyme becomes sterically hindered, causing inhibition that is most pronounced with large substrate molecules. 7. The possible physiological importance of the unique binding characteristics of α2-macroglobulin is discussed.

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