Enzyme-Inhibitor Complex in a Tryptophan-Requiring Mutant of Neurospora crassa

ABSTRACT Two genes, nuc-1 and nuc-2, of Neurospora crassa which were responsible for the nucleic acid digestion, were located on linkage group 1 and 2, respectively. A temperature-sensitive mutant (B1ts-2) was obtained from a nuc-2 mutant. Nuclease mutants showed a reduced activity of nuclease N3 which was found to be a complex consisting of nuclease N3' and inhibitor molecule. Nuclease N3, nuclease N3' and inhibitor were partially purified and estimated to have the approximate molecular weights of 38,000, 12,500 and 25,000 respectively. A nuc-1 mutant produced the nuclease N3' altered in thermolability. A nuc-2 mutant and B1ts-2 produced the inhibitor altered in the capacity to inhibit nuclease N3' activity. The inhibitor prepared from B1ts-2 was more thermostable than that from other strains. From these results, it was suggested that the nuc-1 gene is the structural gene for nuclease N3' and the nuc-2 gene that for the inhibitor. A possible involvement of this enzyme-inhibitor complex in the regulation of nuclease activity and synthesis of other proteins was suggested.

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m-[o-(2-Chloro-5-Fluorosulfonylphenylureido)Phenoxybutoxy]Benzamidine: Affinity Labeling Reagent Which Can Identify Secondary Binding Sites of Coagulation Complement and Fibrinolytic Serine Proteases

10.1055/s-0038-1665767 ◽

1979 ◽

Author(s):

D Bing ◽

D Robison ◽

J Andrews ◽

R Laura

Keyword(s):

Binding Sites ◽

Serine Proteases ◽

Enzyme Inhibitor ◽

Molecular Model ◽

Factor Xa ◽

Affinity Labeling ◽

Catalytic Center ◽

Inhibitor Complex ◽

Polypeptide Chains ◽

Kinetics Of

We have determined that m-[o-(2-chloro-5-fluorosulfonylphenylureido)phenoxybutoxy]benza-midine [mCP(PBA)-F] is an affinity labeling reagent which labels both polypeptide chains of thrombin, factor Xa, complement component CIS and plasmin. As this means it is reacting outside of the catalytic center, we have called this reagent an exo-site affinity labeling reagent. Progressive irreversible inhibition of these enzymes by this reagent is rapid (k1st 2.5-4.6 x 10-3sec-1), the kinetics of inactivation are consistent with inhibition proceding via formation of a specific enzyme-inhibitor complex analogous to a Michaelis-Menton complex (KL - 115-26 μM), and diisopropylfluorophosphate or p-amidino-phenylmethanesulfonyfluoride Prevent labeling by [3H]mCP(PBA)-F. A molecular model of mCP(PBA)-F shows that the reactive SO2F group can be 17 A from the cationic amidine. The data are consistent with the hypothesis that both peptide chains are required for the specific proteolytic activity exhibited by these proteases and that the peptide chain which does not contain the active site serine is close to the catalytic center. (Supported by NIH and AHA grants

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Optimal Duration of the Preincubation Phase in Enzyme Inhibition Experiments

10.26434/chemrxiv.12016974.v1 ◽

2020 ◽

Author(s):

Petr Kuzmic

Keyword(s):

Enzyme Inhibition ◽

Dose Response ◽

Enzyme Inhibitor ◽

Single Point ◽

Association Rate ◽

Weakly Bound ◽

Inhibitor Complex ◽

Dissociation Equilibrium ◽

Optimal Duration ◽

Algebraic Formula

This report describes an algebraic formula to calculate the optimal duration of the pre-incubation phase in enzyme-inhibition experiments, based on the assumed range of expected values for the dissociation equilibrium constant of the enzyme–inhibitor complex and for the bimolecular association rate constant. Three typical experimental scenarios are treated, namely, (1) single-point primary screening at relatively high inhibitor concentrations; (2) dose-response secondary screening of relatively weakly bound inhibitors; (3) dose-response screening of tightly-bound inhibitors.

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A Very Short Hydrogen Bond Provides Only Moderate Stabilization of an Enzyme-Inhibitor Complex of Citrate Synthase

Biochemistry ◽

10.1021/bi00191a002 ◽

1994 ◽

Vol 33 (25) ◽

pp. 7753-7759 ◽

Cited By ~ 47

Author(s):

Ken C. Usher ◽

S. James Remington ◽

David P. Martin ◽

Dale G. Drueckhammer

Keyword(s):

Hydrogen Bond ◽

Citrate Synthase ◽

Enzyme Inhibitor ◽

Inhibitor Complex ◽

Short Hydrogen Bond

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Kinetic properties of the primary inhibitor of plasmin from human plasma

Biochemical Journal ◽

10.1042/bj1630389 ◽

1977 ◽

Vol 163 (2) ◽

pp. 389-391 ◽

Cited By ~ 74

Author(s):

U Christensen ◽

I Clemmensen

Keyword(s):

Human Plasma ◽

Enzyme Inhibitor ◽

Kinetic Properties ◽

Inhibitor Complex ◽

Rapid Formation ◽

Plasmin Inhibitor

The interaction of human plasmin with the newly discovered alpha2-plasmin inhibitor was investigated. It was found from rate measurements that the reaction involves the rapid formation of a first enzyme-inhibitor complex, followed by the slow irreversible transition to another complex. L-Lysine influences the first step, but not the second.

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Internalization of serratial protease into cells as an enzyme-inhibitor complex with alpha 2-macroglobulin and regeneration of protease activity and cytotoxicity.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)60908-1 ◽

1987 ◽

Vol 262 (23) ◽

pp. 10946-10950

Author(s):

H Maeda ◽

A Molla ◽

T Oda ◽

T Katsuki

Keyword(s):

Protease Activity ◽

Enzyme Inhibitor ◽

Inhibitor Complex

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Structure of Enzyme-Inhibitor Complex Determined by Neutron Crystallography

Nihon Kessho Gakkaishi ◽

10.5940/jcrsj.55.47 ◽

2013 ◽

Vol 55 (1) ◽

pp. 47-51

Author(s):

Taro TAMADA ◽

Motoyasu ADACHI ◽

Kazuo KURIHARA ◽

Ryota KUROKI

Keyword(s):

Enzyme Inhibitor ◽

Inhibitor Complex ◽

Neutron Crystallography

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TWO-SIDE IMMUNOASSAYS OF ENZYME-INHIBITOR COMPLEXES FOR THE DIAGNOSIS OF THROMBOPHILIC STATES

10.1055/s-0038-1643113 ◽

1987 ◽

Author(s):

H Bleyl

Keyword(s):

Heart Surgery ◽

Enzyme Inhibitor ◽

Open Heart Surgery ◽

Coagulation Cascade ◽

Clotting Factors ◽

Inhibitor Complex ◽

At Iii ◽

Complex Measurement ◽

Sandwich Assays ◽

Time Of Admission

The diagnosis of prethrombotic states requires methods which detect products of intravasal activation of the coagulation cascade.Two-side immunoassays for antithrombin complexes with clotting factors were developed (IXi-AT, Xi-AT, IIi- AT). These sandwich assays permit the diagnosis of hypercoagulability in the presence or absence of heparin. The biological half live time of the thrombin-antithrombin-complex was found to be about 15 min. Healthy young men 20-25 years old (n=30) have a thrombin-antithrombin-complex concentration of 0.4 ± 0.2 mU/ml thrombin equivalent (S 2238). Patients with acute myocardial infarction (n=40) showed at the time of admission to the hospital up to 10-fold (n=14), up to 100-fold (n=13) more than 100-fold (n=13) elevated thrombin-antithrombin-complex concentrations. Patients with gastrointestinal cancer showed sometime excessive elevated enzyme-inhibitor complexes.No correlation was found between thromboplastine time (Quick) and complex concentration in patients under anticoagulant therapy with dicumarole. In patients under dialysis as well as in patients under open heart surgery with extracorporal circulation, the biocompatibility can be monitored by inhibitor complex measurement.

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