Glycyl tyrosine

Figure 7-3. Two-dimensional representation of a dipeptide substrate, glycyl-tyrosine, bound within the active site of carboxypeptidase A.

T. A. Steitz, and W. N. Lipscomb, The structure of car-boxypeptidase A Some results at 2.0-A resolution, and the complex with glycyl tyrosine at 2.8-A resolution. Proc. Natl. Acad. Sci. USA 58 2220, 1967. 

Vanadium(IV) complexes with two dipeptides glycyl-tyrosine and glycyl-phenylalanine (Gly-Tyr and Gly-Phe, respectively) and their oxovanadium(lV) and (V) complexes have been observed.382, 01 The complex formed with Gly-Tyr showed coordination by the peptide backbone moieties, and no interaction from the distal phenolic hydroxy group.601 A histidine-tyrosine derivatized peptide was shown to complex Viv in a pentadentate manner (120).564 The adduct between VlV and a model of the active-site peptide of protein tyrosine phosphatases has been spectroscopically characterized.602 Similar characterization of in serum suggests that protein complexes form, and that both Viv and Vv can exist as complexes with transferrin and albumin.603 ESEEM has been used to characterize the complexes of apoferritin with V02+ and suggests that the carboxylates, one water molecule, and one histidine ligand fill the coordination sites of the vanadium.604... 

Phenylalanine pH 2.0 Phenylalanine pH 12.0 Tyrosine pH 6.0 Tryptophan pH 2.0 Tryptophan pH12.0 Tyrosyl glycine Glycyl tyrosine Leucyl tyrosine Tyrosyl tyrosine Tyrosine anhydride Tryptophan ethyl ester Glycyl tryptophan pH 2,0... 

All the peptolyrtic enzymes do not react with polypeptids hydrolyzable by pancreatic juice, and here, up to a certain point, we can indicate an action peculiar to each individual. In these investigations, it is useful first of all to bring to the same standard the liquids to be analyzed Take, for example, two active Hquids which act on glycyl-tyrosin. Thar enzymic content will be different, pro-vided the quantity of t)nrosin liberated in a given time from the same quantity of polypeptid and of active Uquid... 

The CD spectrum of glycyl-tyrosine is dominated by the phenol moiety, and only slight differences are observed between the dichroism of this dipeptide and that of the tyrosine. 

We chose carboxypeptidase A (CPA) as the protein to study first because relatively high accuracy X-ray data was available both for the native protein [6] and for the protein with the substrate, glycyl-tyrosine, (gly-tyr) bound to it [7]. 

CieHfo lXsOe Ohloracetyl-alanyl-glycyl-tyrosin 14. 617. 

Figure 16 A model of carboxypeptidase with only alpha-carbons forming the backbone and with selected residues within the active site also displayed. Glycyl-tyrosine is shown in green docked in the active site and amino acid residues that contribute to binding glycyl-tyrosine are shown in red. The dashed line indicates a distance that is being interactively monitored as tyrosine 248 is rotated...

Figure 4. SE-HPLC of a mixture of proteins on SynChropak 100. Column. 250 x 4.6 mm i.d. mobile phase, 0.1 M potassium phosphate, pH 7 flow-rate, 0.25 ml/min. Sample, (1) thyroglobulin (2) alcohol dehydrogenase (3) ovalbumin (4) ribonuclease (5) glycyl tyrosine. O...

L-Pyroglutamyl-L-glutaminyl-L-aspartyl-L-tyrosine azide L-Threonyl-glycyl-L-tryptophanyl-L-methionyl-L-aspartyl-L-phenylalaninamide Pyridine sulfuric anhydride Sodium carbonate... 

Z-Gly - Gly Tyr-OMefL-Tyrosine, N-[N-[N-[(phenyl-methoxy)earbonyl]glycyl]glycyl]-, methyl ester] B 84%... 

Z-Gly.Gly.Gly-OEt [Glycine, V-[W [JV-[ (phenylmethoxy )carbonyl] glycyl] -glycyl] -, ethyl ester], 93 Z-Gly.Gly.Tyr-OMe [L-Tyrosine, JV-[A7-[JV- [ (phenylmethoxy )carbonyI ] glycyl] glycyl] -, methyl ester], 93 Z-Gly-NHBz [Carbamic acid, [2-OXO-2 [(phenylmethyl)amino] ethyl] -, phenylmethyl ester], 93 Z-Gly.DL-Phe.Gly-OEt [Glycine, N-[N-[A -[ (phenylmethoxy [carbonyl ] glycyl] -DL-phenylalanyl)-, ethyl ester],... 

Fig. 11. The slowly hydrolyzed substrate glycyl-L-tyrosine binds to carboxypeptidase A in a nonproductive complex where the amino-terminal glycine complexes the active-site ion (large sphere) to form a five-membered chelate, as in Fig. 10. Protein-bound zinc ligands Glu-72, His-69, and His-196 complete the coordinadon polyhedron of pentacoordinate zinc. Active-site residues are indicated by one-letter abbreviadons and sequence numbers E, glutamate H, hisddine R, arginine Y, tyrosine. [Reprinted with permission from Christianson, D. W., Lipscomb, W. N. (1986) Proc. Natl. Acad. Sci. U.S.A. 83,7568-7572.]...

The tyrosine group can be coupled with p-azobenzenearsonate to give an asymmetric centre. The CD spectrum changes on addition of glycyl-L-tyrosine, showing that the conformation of the azotyrosyl residue is altered on binding of substrate. 

The determination of the crystal structure of carboxypeptidase A and its complex with glycyl-L-tyrosine has been completed to 2.0 A resolution by Lipscomb and coworkes (91). A detailed description of the molecule including a comprehensive discussion of structure-function relations have been presented (91). 

The binding of glycyl-L-tyrosine in the active site pocket of carboxypeptidase A is illustrated in Fig. 15. Tyrosine-248 and glutamic acid-270 are believed to participate in the catalytic reaction and represent the acidic and basic groups, respectively, involved in the bell-shaped pK-rate profile. In the bond-cleavage reaction, the carboxyl group of Glu-270 may act by a nucleophilic attack on the carbonyl group while Tyr-248... 

Fig. 15. Schematic drawing of the active site region of carboxypeptidase A interacting with glycyl-L-tyrosine. From Lipscomb et al. (91) and sequence information from the laboratory of H. Neurath (101).

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