Linked Life Data

11292354

Source:http://linkedlifedata.com/resource/pubmed/id/11292354

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
2001-4-9
pubmed:abstractText
We describe a new serine protease inhibition motif in which binding is mediated by a cluster of very short hydrogen bonds (<2.3 A) at the active site. This protease-inhibitor binding paradigm is observed at high resolution in a large set of crystal structures of trypsin, thrombin, and urokinase-type plasminogen activator (uPA) bound with a series of small molecule inhibitors (2-(2-phenol)indoles and 2-(2-phenol)benzimidazoles). In each complex there are eight enzyme-inhibitor or enzyme-water-inhibitor hydrogen bonds at the active site, three of which are very short. These short hydrogen bonds connect a triangle of oxygen atoms comprising O(gamma)(Ser195), a water molecule co-bound in the oxyanion hole (H(2)O(oxy)), and the phenolate oxygen atom of the inhibitor (O6'). Two of the other hydrogen bonds between the inhibitor and active site of the trypsin and uPA complexes become short in the thrombin counterparts, extending the three-centered short hydrogen-bonding array into a tetrahedral array of atoms (three oxygen and one nitrogen) involved in short hydrogen bonds. In the uPA complexes, the extensive hydrogen-bonding interactions at the active site prevent the inhibitor S1 amidine from forming direct hydrogen bonds with Asp189 because the S1 site is deeper in uPA than in trypsin or thrombin. Ionization equilibria at the active site associated with inhibitor binding are probed through determination and comparison of structures over a wide range of pH (3.5 to 11.4) of thrombin complexes and of trypsin complexes in three different crystal forms. The high-pH trypsin-inhibitor structures suggest that His57 is protonated at pH values as high as 9.5. The pH-dependent inhibition of trypsin, thrombin, uPA and factor Xa by 2-(2-phenol)benzimidazole analogs in which the pK(a) of the phenol group is modulated is shown to be consistent with a binding process involving ionization of both the inhibitor and the enzyme. These data further suggest that the pK(a) of His57 of each protease in the unbound state in solution is about the same, approximately 6.8. By comparing inhibition constants (K(i) values), inhibitor solubilities, inhibitor conformational energies and corresponding structures of short and normal hydrogen bond-mediated complexes, we have estimated the contribution of the short hydrogen bond networks to inhibitor affinity ( approximately 1.7 kcal/mol). The structures and K(i) values associated with the short hydrogen-bonding motif are compared with those corresponding to an alternate, Zn(2+)-mediated inhibition motif at the active site. Structural differences among apo-enzymes, enzyme-inhibitor and enzyme-inhibitor-Zn(2+) complexes are discussed in the context of affinity determinants, selectivity development, and structure-based inhibitor design.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0022-2836
pubmed:author
pubmed:copyrightInfo
Copyright 2001 Academic Press.
pubmed:issnType
Print
pubmed:day
13
pubmed:volume
307
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1451-86
pubmed:dateRevised
2009-11-3
pubmed:meshHeading
pubmed-meshheading:11292354-Amino Acid Motifs, pubmed-meshheading:11292354-Anions, pubmed-meshheading:11292354-Apoproteins, pubmed-meshheading:11292354-Binding Sites, pubmed-meshheading:11292354-Crystallography, X-Ray, pubmed-meshheading:11292354-Drug Design, pubmed-meshheading:11292354-Factor Xa, pubmed-meshheading:11292354-Hydrogen Bonding, pubmed-meshheading:11292354-Hydrogen-Ion Concentration, pubmed-meshheading:11292354-Models, Molecular, pubmed-meshheading:11292354-Phenols, pubmed-meshheading:11292354-Protein Conformation, pubmed-meshheading:11292354-Serine Endopeptidases, pubmed-meshheading:11292354-Serine Proteinase Inhibitors, pubmed-meshheading:11292354-Solubility, pubmed-meshheading:11292354-Static Electricity, pubmed-meshheading:11292354-Substrate Specificity, pubmed-meshheading:11292354-Temperature, pubmed-meshheading:11292354-Thermodynamics, pubmed-meshheading:11292354-Thrombin, pubmed-meshheading:11292354-Trypsin, pubmed-meshheading:11292354-Urokinase-Type Plasminogen Activator, pubmed-meshheading:11292354-Water, pubmed-meshheading:11292354-Zinc
pubmed:year
2001
pubmed:articleTitle
A novel serine protease inhibition motif involving a multi-centered short hydrogen bonding network at the active site.
pubmed:affiliation
Axys Pharmaceuticals Corporation, 385 Oyster Point Boulevard, Suite 3, South San Francisco, CA, 94080, USA. brad_katz@axyspharm.com
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't