title: A low-barrier hydrogen bond in the catalytic triad of serine proteases? Theory versus experiment.
abstract: Cleland and Kreevoy recently advanced the idea that a special type of hydrogen bond (H-bond), termed a low-barrier hydrogen bond (LBHB), may account for the "missing" transition state stabilization underlying the catalytic power of many enzymes, and Frey et al. have proposed that the H-bond between aspartic acid 102 and histidine 57 in the catalytic triad of serine proteases is an example of a catalytically important LBHB. Experimental facts are here considered regarding the aspartic acid-histidine and cis-urocanic H-bonds that are inconsistent with fundamental tenets of the LBHB hypothesis. The inconsistencies between theory and experiment in these paradigm systems cast doubt on the existence of LBHBs, as currently defined, within enzyme active sites.
authors.affiliation: Department of Biochemistry, Tufts University School of Medicine, Boston, MA 02111, USA.
authors.forename: E L
authors.initials: EL
authors.lastname: Ash
authors.forename: J L
authors.initials: JL
authors.lastname: Sudmeier
authors.forename: E C
authors.initials: EC
authors.lastname: De Fabo
authors.forename: W W
authors.initials: WW
authors.lastname: Bachovchin
mesh_terms: D001224:Aspartic Acid / Q000737:chemistry; D001665:Binding Sites; D001897:Boronic Acids / Q000378:metabolism; D002384:Catalysis; D006639:Histidine / Q000737:chemistry; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D009842:Oligopeptides / Q000378:metabolism; D011522:Protons; D012697:Serine Endopeptidases / Q000737:chemistry* / Q000378:metabolism; D015842:Serine Proteinase Inhibitors / Q000378:metabolism; D013381:Subtilisins / Q000737:chemistry; D013696:Temperature; D014560:Urocanic Acid / Q000737:chemistry
chemical_list: D001897:Boronic Acids; D009842:Oligopeptides; D011522:Protons; D015842:Serine Proteinase Inhibitors; D001224:Aspartic Acid; D006639:Histidine; C084716:O-methyl-succinyl-alanyl-alanyl-prolyl-borovaline; D012697:Serine Endopeptidases; D013381:Subtilisins; C021826:myxobacter alpha-lytic proteinase; D014560:Urocanic Acid