No abstract

The frequencies of six platelet-specific antigens among Chinese in Taiwan are reported, which have not previously been well studied. HPA-1a (PlA1) antigen was positive in all 1100 Chinese tested. HPA-4b (Yukb) antigen was positive in all 100 persons tested. HPA-2b (Ko(a), Sib(a)) antigen was positive in 9 percent of 100 persons tested, HPA-3a (Bak(a)) in 77 percent, and NAKa in 96 percent. HPA-4a (Yuk(a)) antigen occurred in 0 percent in this study but is estimated to be present in 0.5 percent of the Taiwanese population.

Polyethylene glycol (PEG) is a polyether compound commonly used in biological research and medicine because it is biologically inert. This simple polymer exists in variable chain lengths (and molecular weights). As they are devoid of any contiguous π-system, PEGs are expected to lack fluorescence properties. However, recent studies suggested the occurrence of fluorescence properties in non-traditional fluorophores like PEGs. Herein, a thorough investigation has been conducted to explore if PEG 20k fluoresces. Results of this combined experimental and computational study suggested that although PEG 20k could exhibit "through-space" delocalization of lone pairs of electrons in aggregates/clusters, formed via intermolecular and intramolecular interactions, the actual contributor of fluorescence between 300 and 400 nm is the stabilizer molecule, i.e., 3-tert-butyl-4-hydroxyanisole present in the commercially available PEG 20k. Therefore, the reported fluorescence properties of PEG should be taken with a grain of salt, warranting further investigation.

In a previous study we showed that the shortened MUC1 mucin peptide GVTSAPD could bind monoclonal antibody (mAb). We proceeded on to make a cyclic peptide of the same sequence to see if it would be more effective in binding antibody. We were able to synthesize and isolate two different cyclic mucin peptides: 1) a monomer cyclic peptide with sequence GVTSAPD which we did not study due to difficulties in achieving homogeneity, and 2) a dimer cyclic peptide with sequence GVTSAPDGVTSAPD that was successfully isolated and studied. We describe here the results of the dimer cyclic peptide-antibody interactions obtained by Saturation Transfer Difference NMR (STDNMR). The results indicated that the protons of all residues experienced STD effects, notably being more pronounced at Pro, Val, Ala and Asp compared to the linear peptide GVTSAPD. The Pro residue exhibited STD peaks for all its side chain protons with stronger intensity at ProHγ while Ala, Val and Thr are localized to methyl groups. KEYWORDS: Muc1 Antibody Recognition Epitope, STD NMR, Mucin Peptide-antibody Interactions, Cyclodimer Peptide.