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  • 1
    Electronic Resource
    Electronic Resource
    Functional properties of a hemoglobin carrying heme only on α-chains (1968)
    s.l. : American Chemical Society
    Biochemistry 7 (1968), S. 2228-2232 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00846a027
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  • 2
    Electronic Resource
    Electronic Resource
    Catalytic and ligand binding properties of bovine trypsinogen and its complex with the effector dipeptide Ile-Val (1984)
    Springer
    Molecular and cellular biochemistry 60 (1984), S. 163-181 
    Details
    ISSN: 1573-4919
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary Steady-state and pre-steady-state kinetic data for the trypsinogen catalyzed hydrolysis of a series of synthetic substrates (i.e. p-nitrophenyl esters of N-α-carbobenzoxy-L-amino acids) have been obtained as a function of pH (3.4–8). Moreover, the effect of ethylamine on the hydrolysis of a neutral substrate and benzamidine binding have been extensively studied. In order to obtain direct information on the transition of trypsinogen to a β-trypsin-like structure, the role of the effector dipeptide Ile-Val on the catalytic and ligand binding properties of the zymogen has been investigated. Kinetic and thermodynamic data for β-trypsin and α-chymotrypsin are also reported for the purpose of an homogeneous comparison of the various (pro)enzymes. Under all the experimental conditions, kinetic data for (pro)enzyme catalysis are consistent with the minimum three-step mechanism: $$E + S\mathop \rightleftharpoons \limits_{k_{ - 1} }^{k_{ + 1} } E.S\mathop \rightleftharpoons \limits_{k_{ - 2} }^{k_{ + 2} } \mathop E\limits_{\mathop + \limits_{P_1 } } .P\mathop \rightleftharpoons \limits_{k_{ - 3} }^{k_{ + 3} } E + P_{2,}$$ involving the acyl intermediate E.P. In the presence of Ile-Val dipeptide, trypsinogen assumes catalytic and ligand binding properties that are reminiscent of activated β-trypsin. This is at variance with free trypsinogen, which shows a α-chymotrypsin-like behavior. The large differences in the results of kinetic and thermodynamic measurements for free trypsinogen, as compared to its binary adduct with Ile-Val, can be ascribed to the substantial differences in the two molecular species, which include the spatial orientation of Asp189.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222487
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  • 3
    Electronic Resource
    Electronic Resource
    Binding of organic ions by proteins (1981)
    Springer
    Molecular and cellular biochemistry 36 (1981), S. 143-146 
    Details
    ISSN: 1573-4919
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary The oxygen equilibrium of human hemoglobin has been studied in the presence of 1-benzyl-3-indazoleoxyacetate (BZ). The results show that: (a) The overall oxygen affinity of hemoglobin is a function of BZ concentration, but the cooperative character of the equilibrium curve appears insensitive to the drug up to the maximal concentration studied (5 × 10−2 M); (b) The functional expression of the interaction between hemoglobin and BZ is not affected by the presence of protons, i.e., the change in oxygen affinity determined by BZ is the same at any pH value studied; (c) The aromatic region of BZ molecules is of primary importance for the functional change of hemoglobin; (d) The difference in moles of BZ bound per mole of tetrameric unliganded and oxygenated hemoglobin corresponds to 2; these functionally relevant binding sites on the protein are probably located at α1, β1 and α2β2 interfaces; (e) Thermodynamically, entropy effects dominate the reaction between hemoglobin and BZ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02357030
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  • 4
    Electronic Resource
    Electronic Resource
    Benzamidine as a spectroscopic probe for the primary specificity subsite of trypsin-like serine proteinases (1984)
    Springer
    Molecular and cellular biochemistry 64 (1984), S. 139-144 
    Details
    ISSN: 1573-4919
    Keywords: benzamidine ; benzamidine displacement (from bovine β-trypsin) ; benzamidine displacement (upon BPTI binding) ; bovine basic pancreatic trypsin inhibitor (BPTI, Kunitz) ; bovine β-trypsin ; kinetics of bovine β-trypsin: BPTI complex formation ; spectroscopic probe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary Formation and dissociation of the benzamidine: β-trypsin adduct is accompanied by reversible spectral changes in the ultraviolet region (between 230 and 300 nm). The pH-independent difference extinction coefficient of the adduct (benzamidine: β-trypsin complex minus the free proteinase) is 1.75 mM−1 cm−1 at 248 nm. This signal can be used in studies of inhibitor and substrate binding by rapid kinetic techniques. Therefore, following the spectral changes associated with the displacement of benzamidine from the primary specificity subsite, the kinetics of the β-trypsin: BPTI complex formation were investigated between pH 2.9 and 7.6 (I = 0.1 M) at 21 ± 0.5 °C. Under all the experimental conditions the β-trypsin: BPTI complex formation, examined by benzamidine displacement experiments, may be described in terms of a simple competition event. On the other hand, the very same reaction followed by displacement of another spectroscopic probe, proflavine, appears to involve the ternary proflavine: β-trypsin:BPTI adduct (7). The difference between the kinetic processes of β-trypsin: BPTI complex formation, observed by using benzamidine and proflavine as reaction indicators, suggests that the two dye molecules bind at non-coincident regions of the proteinase active center. The advantages in using benzamidine as a sensitive probe specific for the S1 subsite of the recognition center of trypsin-like proteinases, as compared to proflavine, are emphasized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224770
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  • 5
    Electronic Resource
    Electronic Resource
    X-ray crystal structure of the bovine α-chymotrypsin/eglin c complex at 2.6 Å resolution (1990)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 3 (1990), S. 163-168 
    Details
    ISSN: 0952-3499
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The crystal structure of the molecular complex formed by bovine α-chymotrypsin and the recombinant serine proteinase inhibitor eglin c from Hirudo medicinalis has been solved using monoclinic crystals of the complex, reported previously. Four circle diffractometer data at 3.0 Å resolution were employed to determine the structure by molecular replacement techniques. Bovine α-chymotrypsin alone was used as the search model; it allowed us to correctly orient and translate the enzyme in the unit cell and to obtain sufficient electron density for positioning the eglin c molecule. After independent rigid body refinement of the two complex components, the molecular model yielded a crystallographic R factor of 0.39. Five iterative cycles of restrained crystallographic refinement and model building were conducted, gradually increasing resolution. The current R factor at 2.6 Å resolution (diffractometer data) is 0.18. The model includes 56 solvent molecules. Eglin c binds to bovine α-chymotrypsin in a manner consistent with other known serine proteinase/inhibitor complex structures. The reactive site loop shows the expected conformation for productive binding and is in tight contact with bovine α-chymotrypsin between subsites P3 and P′2; Leu 45I acts as the P1 residue, located in the primary specificity S1 site of the enzyme. Hydrogen bonds equivalent to those observed in complexes of trypsin(ogen) with the pancreatic basic- and secretory- inhibitors are found around the scissile peptide bond.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmr.300030405
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  • 6
    Electronic Resource
    Electronic Resource
    Binding of the recombinant proteinase inhibitor eglin c from leech Hirudo medicinalis to serine (Pro)enzymes: A comparative thermodynamic study (1991)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 4 (1991), S. 113-119 
    Details
    ISSN: 0952-3499
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The binding of the recombinant proteinase inhibitor eglin c from the leech Hirudo medicinalis to serine (pro)enzymes belonging to the chymotrypsin and subtilisin families has been investigated from the thermodynamic viewpoint, between pH 4.5 and 9.5 and from 10°C to 40°C. The affinity of eglin c for the serine (pro)enzymes considered shows the following trend: Leu-proteinase [the leucine specific serine proteinase from spinach (Spinacia oleracea L.) leaves] 〉 human leucocyte elastase ⋍ human cathepsin G ⋍ subtilisin Carlsberg ⋍ bovine α-chymotrypsin 〉 bovine α-chymotrypsinogen A ⋍ porcine pancreatic elastase ⋍ bovine β-trypsin. The serine (pro)enzyme-inhibitor complex formation is an entropy-driven process. On increasing the pH from 4.5 to 9.5, the affinity of eglin c for the serine (pro)enzymes considered increases thus reflecting the acid pK shift to the invariant hystidyl catalytic residue from ≍ 6.9 in the free serine proteinases and bovine α-chymotrypsinogen A to ⋍ 5.1 in the serine (pro)enzyme-inhibitor complexes. Considering the known molecular models, the observed binding behaviour of eglin c was related to the inferred stereochemistry of the serine(pro)enzyme-inhibitor contact regions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmr.300040402
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  • 7
    Electronic Resource
    Electronic Resource
    Selective oxidation of methionyl residues in the human recombinant secretory leukocyte proteinase inhibitor. Effect on the inhibitor binding properties (1994)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 7 (1994), S. 31-37 
    Details
    ISSN: 0952-3499
    Keywords: Bovine α-chymotrypsin ; Bovine β-trypsin ; Human recombinant secretory leukocyte proteinase inhibitor ; Methionine oxidation ; Proteinase:inhibtor complex (de)stabilization ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Binding of the human recombinant secretory leukocyte proteinase inhibitor (SLPI) [native and with the methionyl residues at positions 73, 82, 94 and 96 of domain 2 oxidized to the sulfoxide derivative (Met(O) SLPI)] to bovine α-chymotrypsin (α-chymotrypsin) [native and with the Met192 residue converted to the sufoxide derivative (Met(O) α-chymotrypsin)] as well as to native bovine β-trypsin (β-trypsin), which does not contain methionyl residues, has been investigated between pH 4.0 and 8.0, and between 10.0°C ad 30.0°C, from thermodynamic and/or kinetic viewpoints. By increasing the number of oxidized methytonyl residues present at the proteinase: inhibitor contact interface (from 0 to 3), the adducts investigated are increasingly destabilized and the relaxation time of the complexes into conformers less stable is enhanced. On the other hand, the selective oxidation methionyl residues of SLPI and α-chymotrypsin, by the reaction with chloramines T, does not affect the proteinase inhibition recognition mechanism. Therefore, even though conformational changes may occur in the conversion native SLPI and native α-chymotrypsin to their Met(O) derivatives, a localized steric hindrance can be considered as the main structural determinant accounting for the reported results.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmr.300070105
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  • 8
    Electronic Resource
    Electronic Resource
    Binding of native and [homoserine lactone-52]-52,53-seco-bovine basic pancreatic trypsin inhibitor (kunitz inhibitor) to porcine pancreatic β-kallikrein-B and bovine α-chymtorpsin: Thermodynaic study (1994)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 7 (1994), S. 39-46 
    Details
    ISSN: 0952-3499
    Keywords: Neuraminidase-treated porcine pancreatic β-kallikrein-B ; Bovine α-chymotrypsin ; Native bovine basic pancreatic trypsin inhibitor ; [Homoserine lactone-52]-52,53-seco-bovine basic pancreatic trypsin inhibitor ; Serine proteinase inhibition ; Thermodynamics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Values of the association equilibrium constant (Ka) for the binding of the native and of the cyanogen bromide-cleaved bovine basic pancreatic trypsin inhibitor (native BPTI and [Hse lactone-52]-52,53-seco-BPTI, respectively) to neuraminidase-treated porcine pancreatic β-Kallikrein-B (kallikrein) and bovine α-chymotrypsin (chymotrypsin) have been determined between pH4.0 and 9.0, and 20.0°C. Over the whole pH range explored, native BPTI and [Hse lactone-52]-52,53-seco-BPTI show the same affinity for kallikrein. On the other hand, the affinity of [se lactone-52]-52,53-seco-BPTI for chymotrypsin is high4er, around neutrality, than that found for native BPTI by about one order of magnitude, coverging in the acidic pH limb. The simplest mechanism accounting for the observed data implies that, on lowering the pH from 9.0 to 4.0 (i) the decrease in affinity for the binding of native BPTI to kalikrein and chymotrypsin, as well as for the association of [Hse lactone-52]-52,53-seco-BPTI to kalikrein, reflects the acidic pK shift, upon inhibitor association, of a single inozing group; and (ii) the decrease of Ka values for [Hse lactone-52]-52,53-seco-BPTI binding to chymotrypsin appears to be modulated by the acidic pK shift, upon inhibitor association, of two non-equivalent proton-binding residues. On the basis of the stereochemistry of the serine proteinase/inhibitor contact region(s), these data indicate that long-rang structural changes in [Hse lactone-52]-52,53-seco-BPTI are energetically linked to the chymotrypsin: inhibitor complex formation. This observation represents an important aspect for the mechanism of molecular recognition and regulation in BPTI.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmr.300070106
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  • 9
    Electronic Resource
    Electronic Resource
    Binding of the kunitz-type trypsin inhibitor DE-3 from Erythrina caffra seeds to serine proteinases: a comparative study (1992)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 5 (1992), S. 105-114 
    Details
    ISSN: 0952-3499
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The effect of pH and temperature of kinetic and thermodynamic parameters (i.e.,kon,koff,Ka, δGo, δHo and δSo values) for the binding of the kunitz-type trypsin inhibitor DE-3 from Erythrina caffra seeds (ETI) to bovine β-trypsin, bovine α-chymotrypsin, the human tissue plasminogen activator, human α-, β- and γ-thrombin, as well as the Mr 33000 and Mr 54 000 species of the human urinary plasminogen activator (also named urokinase) has been investigated. At pH 8.0 and 21.0 °C: (i) values of the second-order rate constant (Kon) for the proteinase: ETI complex formation vary between 8.7 × 105 and 1.4 × 107/M/s; (ii) values of the dissociation rate constant (koff) for the proteinase: ETI complex destabilization range from 3.7 × 10-5 to 1.4 × 104/s; and (iii) values of the association equilibrium constant (Ka) for the proteinase: ETI complexation change from 〈 1.0 × 104 to 3.8 × 1011/M. Thus, differences in koff values account mostly for the large changes in Ka values for ETI binding. The affinity of ETI for the serine proteinases considered can be arranged as follows: bovine β-trypsin 〉 human tissue plasminogen activator 〉 bovine β-chymotrypsin » human α-, β- and γ-thrombin ≍ o Mr 33 000 and Mr 54000 species of the human urinary plasminogen activator. Moreover, the serine proteinase: ETI complex formation is an endothermic, entropy-driven, process. On increasing the pH from 5.0 to 9.0 (at 21.0 °C), the affinity of ETI for bovine β-trypsin, the human tissue plasminogen activator and bovine α-chymotrypsin (i.e., Ka values) increases, thus reflecting the acidic-pK shift of the His57 catalytic residue from ≍≍ 7.0, in the free enzymes (pKUNL), to ≍5.2, in the serine proteinase: ETI complexes (pKLIG). The ETI-binding properties have been analysed in parallel with those of related serine (pro)enzyme/macromolecular inhibitor systems. Considering the known molecular models, the observed binding behaviour of ETI is discussed in relationship to the inferred stereochemistry of the serine proteinase/inhibitor contact regions.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmr.300050306
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  • 10
    Electronic Resource
    Electronic Resource
    Binding of the soybean Bowman-Birk proteinase inhibitor and of its chymotrypsin and trypsin inhibiting fragments to bovine α-chymotrypsin and bovine β-trypsin. A thermodynamic study (1990)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 3 (1990), S. 192-196 
    Details
    ISSN: 0952-3499
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The effect of pH and temperature on the apparent association equilibrium constant (Ka) for the binding of the soybean Bowman-Birk proteinase inhibitor (BBI) and of its chymotrypsin and trypsin inhibiting fragments (F-C(p), F-T(p) and F-T(t), respectively) to bovine α-chymotrypsin (α-chymotrypsin) and bovine β-trypsin (β-trypsin) has been investigated. On the basis of Ka values, the proteinase inhibitor affinity can be arranged as follows: β-chymotrypsin: BBI ≈ β-trypsin:BBI ≈ β-trypsin:F-T(t) ≈ β-trypsin:F-T(p) ≫ α-chymotrypsin:F-C(p), F-C(p), F-T(p) and F-T(t) do not inhibit β-trypsin and α-chymotrypsin action, respectively. On lowering the pH from 9.5 to 4.5, values of Ka for BBI, F-C(p), F-T(p) and/or F-T(t) binding to α-chymotrypsin and β-trypsin decrease, thus reflecting the acid-pK shift of the invariant His57 catalytic residue from 7.0, in the free enzymes, to 5.2, in the proteinase:inhibitor complexes. Considering the known molecular models, the observed binding behaviour of BBI, F-C(p), F-T(p) and F-T(t) was related to the inferred stereochemistry of the proteinase:inhibitor contact regions.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmr.300030504
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