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Many small peptides can be displayed on every copy of the major coat protein in recombinant filamentous bacteriophages but larger peptides can only be accommodated in hybrid virions mixed with wild-type protein subunits. A peptide insert of 12 residues capable of display at high copy number in a hybrid virion was found to be incapable of supporting recombinant virion assembly, a defect that could not be overcome by over-expressing leader peptidase in the same Escherichia coli cell. In contrast, over-expressing leader peptidase did increase the copy number of two 9-residue peptides that were poorly incorporated into hybrid virions. The factors that limit peptide display are varied and not restricted to the early stages of viral assembly.z 1998 Federation of European Biochemical Societies.

The human class I MHC molecules are known to generally exist on the cell surface either as peptide-containing complexes of H chain (α-chain) and β2-microglobulin (β2m) or as β2m-free H chains incapable of binding peptides. In this study, a uniquely conformed peptide-containing β2m-free HLA-B2705 H chain has been isolated using the recently described highly efficient perfusion-affinity chromatography system for purification of class I MHC protein molecules. This form recognized by the mAb MARB4 is very closely associated with the remainder of the peptide containing HLA-B2705/β2m complex reactive with mAb ME1 and is present to ∼1–10% of mAb ME1 reactive forms on the cell surface. Also, HLA-B2705 purified using the mAb ME1 affinity column includes this unique mAb MARB4-reactive, unusually stable peptide-containing β2m-free form. A peptide nonamer GRWRGWYTY was isolated and identified from this β2m-free HLA-B2705 H chain and was used to assemble the mAb MARB4 reactive form efficiently on the surface of cells expressing HLA-B2705. The discovery of this form opens new avenues for further investigation of the role of HLA-B27 in spondyloarthropathies.

Oligonucleotide arrays are powerful tools to study changes in gene expression for whole genomes. These arrays can be synthesized by adapting photolithographic techniques used in microelectronics. Using this method, oligonucleotides are built base by base directly on the array surface by numerous cycles of photodeprotection and nucleotide addition. In this paper we examine strategies to reduce the number of synthesis cycles required to construct oligonucleotide arrays. By computer modeling oligonucleotide synthesis, we found that the number of required synthesis cycles could be significantly reduced by focusing upon how oligonucleotides are chosen from within genes and upon the order in which nucleotides are deposited on the array. The methods described here could provide a more efficient strategy to produce oligonucleotide arrays.