Glycyl residue

Comparisons between these toxins allow delineation of the variability of each position in the sequence. For instance, the residues which are extremely invariant (conservative) for both types of sea anemone toxin are the half-cystines, certain glycyl residues which are expected to be involved in )9-turns, and only a few other residues - Asp 5 or 6, Arg 13 or 14, and Tryp 30 or 31 (the numbering depends upon the toxin type) — expected to be important for folding or receptor binding. Rather surprising is the variation in the residues which NMR studies (22,23) have shown are involved in formation of the four stranded )9-pleated sheet. 

Y-chains which differ from the 3-chalns In 39 positions The formula of Hb-F can be written as a2Y2 A minor hemoglobin fraction, Hb-Fi, which Is present for about 7 to 10 percent In a cord blood sample, has the structure of U2Y2 y Indicating that the NH2 terminal glycyl residue of the y-chaln Is acetylated Recently the existence of two structurally different Y-chalns has been demonstrated these two chains (the -and differ at a minimum In one position, namely... 

Figure 2. C-13 chemical shifts of the glycyl residues in [2-[2-C-13]glycine]me-thionine enkephalin and [3-[2-C-13]glycine]methionine enkephalin in the presence of 75.0 and 78.5 mg of PS, respectively, as a function of pH, 30°C. Shifts observed for enkephalin in the absence of PS (see Figure 3), (-------...

Rotational correlation times obtained from the observed C Ti values of the glycyl residues in methionine enkephalin as a function of "pH" are given in Figure 6. The 3-glycyl residue... 

Weigh 4 mg of a monochloroacetylglycyl peptide (MCA-Gly peptide, peptide carrying a MCA-glycyl residue at the N-terminus) into an Eppendorf tube and add the activated KLH or other iminothiolane-activated carrier protein. Shake vigorously at RT for 3 h. Dialyze the reaction mixture twice at RT against PBS for 1 h each. Calculate protein concentration from 235-, 260-, and 280-nm readings (cf. Protocol 1.1.7). 

The reaction cycle of these enzymes begins with reduction of both coppers from Cu(II) to Cu(I) (Eq. 18-54, step a). Both 02 and substrate bind (steps b and c, but not necessarily in this order). The 02 bound to CuB is reduced to a peroxide anion that remains bound to CuB. Both CuA and CuB donate one electron, both being oxidized to Cu(II). These changes are also included in step c of Eq. 18-54. One proposal is that the resulting peroxide is cleaved homolytically while removing the pro-S hydrogen of the glycyl residue. 

FlO. 19. Energy contours for a glycyl residue. The units of energy are keal mole-1. The symbols R and L indicate the locations of the standard right- and left-handed a-helical conformations (Scott and Scheraga, 1966c). 

Figure 13 Plot of the conformations of 560 glycyl residues (from X-ray structures of proteins) in the conventional (< >,i >) map.

The introduction of glycyl residues into proteins with the Leuchs anhydrides of glycine makes peptide bonds next to serine susceptible to cleavage by trypsin (Shalitin, 1961). 

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