Lysin dimer

The crystal structure of the lysin dimer resembles an extended S shape when viewed along its local twofold axis, which relates the helical bundles of the two monomers (Figure 13A Shaw et al., 1995). When viewed ifom the side, the dimer is essentially flat on one side and slightly convex on the other (Figure 13B). A polar view of the dimer emphasizes the asymmetric clustering of the hydrophobic patches of the two monomers (Figure 13C). The four termini of the two monomers... 

Figure 13. Three views of the crystal structure of the lysin dimer. The hydrophobic patch and basic track residues are depicted as in Figures 11 and 12. Arg Lys", and Lys are not visible in the structure of the dimer. (A) View along the local twofold axis relating monomers of the dimer. Residues of the hydrophobic patch interdigitate at the dimer interface while residues of the basic tracks are on opposite surfaces of the dimer. (B) The dimer viewed from the side, showing that one side of the dimer is essentially flat and the opposite side slightly convex. (C) The polar view of the dimer showing the hydrophobic patch residues are clustered to one side of the dimer and all four termini in proximity on the same face of the dimer are shown in the central region at the bottom of the structure (from Shaw et al., 1995).

Figure 14. Kinetics of lysin dimer dissociation when isolated VEs are added to a cuvette with fluorescently labeled lysin. Vertical axis, relative EITC fluorescence horizontal axis, seconds after VE addition. The increased fluorescence emission (release of quenching) indicates dissociation of the dimer. The immediate increase in signal could not be captured, lagged trace is the actual measurements and the smooth trace the fit of the data to a single exponential equation showing a t,/ of approximately 30 seconds (from Shaw etal., 1995).

Shaw, A., Fortes, P.G.A., Stout, C.D., and Vacquier, V.D. (1995). Crystal structure and subunit dynamics of the abalone sperm lysin dimer Egg envelopes dissociate dimers. J. Cell Biol. 750 1117-1126. 

The reaction of two lysyl residues with two molecules of glucose creates the so-called crossline (cross-linked AGE) (4-233), which is found in the serum and kidneys of diabetic patients. An analogous structure, called fluorolink (4-234), actually arises by dehydration and oxidation of crossline. Another cross-linked AGE is imidazolium salt of glyoxal-lysine dimer, trivially called GOLD (4-235), which is 2-ammonio-6-(l-(5-ammonio-6-oxido-6-oxohexyl) imidazolium-3-yl]hexanoate. The compound known as MOLD, (2-ammonio-6-[l-(5-ammonio-6-oxido-6-oxohexyl)-4-methyHmidazolium-3-yl] hexanoate (4-236), results from the analogous reaction with methylglyoxal. These examples, however. 

Fig. 10. Sequences (see Table 1) of betabeUins. In each case, only one-half of the P-sandwich is shown. The dimer is formed from identical monomeric sets of four P-strands. In the pattern sequence, e is for end, p is for polar residue, n is for nonpolar residue, and t and r are for turn residues. Lower case f is iodophenyialanine lower case a, d, k, and p are the D-amino acid forms of alanine, aspartic acid, lysine, and proline, respectively B is P-alanine (2,53,60,61).

A disadvantage of the glutaraldehyde condensation method is that dimers of the hapten and polymers of carrier protein may also form. To overcome this problem, the reaction time is limited to 2-3 h, or an excess of an amine-containing compound, e.g., lysine or cysteamine hydrochloride, is added. A two-step approach also minimizes dimerization. ... 

L-piperidine-2-carboxylic acid is a non-proteinogenic amino acid that is a metabolite of lysine. The zinc complexes of DL-piperidine-2-carboxylic acid, DL-piperidine-3-carboxylic acid, and piperidine-4-carboxylic acid have been studied. The X-ray crystal structures have been determined for the latter two. [ZnCl2(DL-piperidine 3-carboxylate)2] (42) is monomeric with a tetrahedral metal center and monodentate carboxylates. [Zn2Cl4(piperidine-4-carboxylate)2] (43) contains two bridging carboxylates in a dimeric structure. IR studies suggest that the DL-piperidine-2-carboxy-lato zinc has monodentate carboxylate ligands coordinating.392... 

The question of the stability of the biomolecules is a vital one. Could they really have survived the tremendous energies which would have been set free (in the form of shock waves and/or heat) on the impact of a meteorite Blank et al. (2000) developed a special technique to try and answer this question. They used an 80-mm cannon to produce the shock waves the shocked solution contained the two amino acids lysine and norvaline, which had been found in the Murchison meteorite. Small amounts of the amino acids survived the bombardment , lysine seeming to be a little more robust. In other experiments, the amino acids aminobutyric acid, proline and phenylalanine were subjected to shock waves the first of the three was most stable, the last the most reactive. The products included amino acid dimers as well as cyclic diketopiperazine. The kinetic behaviour of the amino acids differs pressure seems to have a greater effect on the reaction pathway than temperature. As had been recognized earlier, the effect of pressure would have slowed down certain decomposition reactions, such as pyrolysis and decarboxylation (Blank et al., 2001). 

---