A poly(L-glutamic acid)-functionalized monolayer 1 has the ability t o capture a-amino acids enantioselectively in aqueous solution due t o a highly assembled structure of the a-helical poly(L-glutamic acid) segments at the monolayer surface.
The putrescine N-methyltransferase (PMT) cDNA clone previously isolated from tobacco encodes a spermidine synthase-like protein with an 11 amino acid element repeated four times in tandem at the amino terminus. Genomic Southern blot analyses indicated that this N-terminal repeat array is found in tobacco PMTs but absent in Hyoscyamus and Atropa PMTs. A truncated tobacco PMT in which this repeat array was entirely removed still retained full enzymatic activity when expressed in Escherichia coli. Three PMT genes (NsPMT1, NsPMT2, NsPMT3) isolated from Nicotiana sylvestris encode two, five, and nine tandem repeats, respectively, in the first exon, but otherwise encode highly conserved proteins. Analysis of PCR fragments amplified from the genomes of N. tabacum and its two probable progenitors shows that one of the nine repeat elements in NsPMT3 was precisely deleted in the corresponding N. tabacum gene. These results indicate that direct tandem repeats of a 33 bp sequence that encodes 11 amino acids of no obvious function were added to the ancestral Nicotiana PMT gene, and that the tandem repetition was genetically very unstable, contracting or expanding during evolution of the Nicotiana species.
Three sibs born to normal but consanguinous parents had flexion deformities of the thumb and fingers on one hand and sensory deficit in the other hand. Extensor muscles were absent or vestigial in all of them. Polyneuropathic electrophysiological findings were detected in 4 limbs. This is an apparently autosomal recessive trait previously unreported.
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