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Three members of the chimpanzee TPI (encoding triosephosphate isomerase) gene family, the transcription unit and two processed pseudogenes, have been characterized by genomic blotting and nucleotide sequence analysis. The bona fide TPI gene spans 3.5 kb with seven exons and six introns, and is the first hominoid TPI gene to be completely sequenced. The chimpanzee gene exhibits a very high degree of sequence identity with human and rhesus TPI genes. For example, the polypeptides of 248 amino acids (aa) encoded by the chimpanzee and human TPI genes are identical, but the codons for five of these aa differ in the third codon wobble position. No alternative splice sites could be identified in the intervening sequences of the gene and, thus, the molecular basis for the synthesis of the proliferation-specific TPI isozyme observed in hominoids remains elusive. An Alu member occurs upstream from one of the processed pseudogenes, and short sequences with significant identity to the primate LINE-1 element flank the region encompassing the Alu member and TPI pseudogene. A solitary endogenous retroviral long terminal repeat occurs within the structural region of the other processed pseudogene. The ages of the processed pseudogenes are estimated to be 2.6 and 10.4 million years, implying that one was inserted into the genome before and one after the divergence of the chimpanzee and human lineages.

The pH dependence of the proton NMR spectrum of [Asn1, Val5] angiotensin II in aqueous solution shows the existence of one major and one minor conformation above pH 6.5, the minor conformation representing 12 +/- 2% of the total peptide. A similar observation has been made for (Asn1, Val5) angiotensin I and Val-Tyr-Val-His-Pro-Phe. This effect is not due to the presence of angiotensin-like impurities in the peptide samples. We have shown two expected impurities, [beta-Asp1, Val5] angiotensin II and [Asn1, 3-Bzl-Ty4, Val5] - angiotensin II, to be absent, and a third impurity [Asn1, Val5, D-His6] angiostensin II, to be present at less than or equal to 2.1 mol%, too little to account for the observed amount (12 +/- 2%) of minor conformation. The carbon-13 spectrum of the hexapeptide at high pH shows that the major conformation has Pro7 in the trans form and the minor conformation has Pro7 in the cis form.

A human genomic DNA clone hybridizing to mammalian valine tRNA(IAC) contained a cluster of three tRNA genes. Two valine tRNA genes with anticodons of AAC and CAC, encoding the major and minor cytoplasmic valine tRNA isoacceptors, respectively, and a lysine tRNA(CUU) gene were identified by Southern blot hybridization and DNA sequence analysis of a 7.1-kb region. At least nine Alu family members were interspersed throughout the 18.5-kb human DNA fragment, with three Alu elements in the intergenic region between the valine tRNA(AAC) gene and the lysine tRNA gene. Each of the five Alu family members in the sequenced region can be categorized into one of the four Alu subfamilies. The coding regions of all three tRNA genes contain characteristic internal split promoter sequences and typical RNA polymerase III termination signals in the 3'-flanking regions. The tRNA genes are accurately transcribed by RNA polymerase III in a HeLa cell extract, since the RNase T1 fingerprints of the mature-sized tRNA transcription products are consistent with the structural genes. The lysine tRNA(CUU) gene was transcribed only slightly more efficiently than the valine tRNA(CAC) gene in the homologous in vitro transcription system. Surprisingly, the valine tRNA(CAC) gene was transcribed about eightfold more efficiently than the valine tRNA(AAC) gene, implicating the presence of a modulatory element in the upstream region flanking the tRNA(CAC) gene.

A cluster of three tRNA genes encoding a tRNA(UGUThr), a tRNA(UGGPro), and a tRNA(AACVal), and two Alu-elements occur in a 6.0-kb human DNA fragment. The tRNA(Thr) gene is 2.7-kb upstream from the tRNA(Pro) gene, which is separated by 367 bp from the tRNA(Val) gene. One Alu-element actually overlaps the tRNA(Val) gene and is of opposite polarity to all three tRNA genes. All three tRNA genes are accurately transcribed in a homologous HeLa cell extract, since the ribonuclease T1 fingerprints of the tRNA transcripts are consistent with the nucleotide sequences of the tRNAs. The upstream region flanking the tRNA(Thr) gene has two tracts of alternating purine/pyrimidine residues potentially capable of adopting the Z-DNA conformation, and presumptive binding sites for two RNA polymerase II transcription factors. The tRNA(Thr) gene apparently has a substantially higher in vitro transcriptional efficiency than the other two tRNA genes in this cluster, and a tRNA(GCCGly) gene from another human DNA segment. Deletion constructs of the tRNA(Thr) gene retaining 272, 168, and 33 bp of original 5'-flanking DNA had about the same in vitro transcriptional efficiency, whereas that of the construct with only 2 bp of 5'-flanking human DNA was drastically reduced. The tRNA(Thr) gene constructs with 272 and 168 bp of original 5'-flanking DNA apparently reduce the transcriptional efficiencies of the proline and glycine tRNA genes, implicating the upstream region from the tRNA(Thr) gene as being crucial for its high transcriptional efficiency.

It has been shown that thin-film dialysis can be performed in such a way that the limiting rate is the rate of entry of the solute into the membrane from the high-concentration side. The rate of diffusion, therefore, reflects the probability of a molecule entering the pores on the surface and does not depend on the resistance to diffusion offered by the internal structure of the membrane. The good correlation, so generally found, of the order of escape times of given solutes with the order of free diffusion rates is thus explained. The data from stretching experiments with wet cellophane, in which the pore structure is distorted, are also explained.