High impact information on Histidylglycine

• In order to determine whether bovine, rabbit, and monkey myelin basic proteins (BPs) have the sequence Gly-His or His-Gly at positions corresponding to bovine sequence 76-77, we isolated the tryptic peptides encompassing the sequence in question in these proteins and cleaved them into dipeptides with dipeptidyl aminopeptidase I (EC 3.4.14.1) [1].
• Structural integrity of the conserved His-Gly dipeptide of lipases also appears to be important for neutral lipid hydrolysis, as replacement of His65 by glutamine abolished HLAL and HGL enzymic activity [2].
• With this approach, the reactivity of the alpha-amino group of histidylglycine toward 1-fluoro-2,4-dinitrobenzene gave an apparent pKa value of 7.64 +/- 0.07 at 37 degrees C, in good agreement with a value of 7.69 +/- 0.02 obtained by acid-base titration [3].
• We show by site-directed mutagenesis that the catalytic residues of mammalian legumain, a recently discovered lysosomal asparaginycysteine endopeptidase, form a catalytic dyad in the motif His-Gly-spacer-Ala-Cys [4].
• When the dipeptide His-Gly was used instead, a similar ageing phenomenon was observed, but with much reduced kinetics [5].

Biological context of Histidylglycine

• This enzyme contains a Ser-centered consensus sequence and a conserved His-Gly dipeptide found in most lipase amino-terminal domains [6].
• The light chain of H-prekininogen contains a characteristic 15-repeated His-Gly sequence and a conserved sequence for binding prekallikrein or factor XI [7].

Associations of Histidylglycine with other chemical compounds

• Both 1H NMR and circular dichroism pH titration studies on histidine, His-Gly, Gly-His and Gly-His-Gly indicate that the side-chain spatial orientation depends strongly on the vicinal charges [8].
• Both these groups in secretin had pK values which were shifted one pK unit higher than in histidylglycine, but like the model compound the reactivity of the imidazole function was still linked to the state of ionization of the alpha-amino group [9].

References