J. E. Heckman

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The RNA cleavage reaction catalyzed by the hairpin ribozyme shows biphasic kinetics, and chase experiments show that the slow phase of the reaction results from reversible substrate binding to an inactive conformational isomer. To investigate the structural basis for the heterogeneous kinetics, we have developed an enzymatic RNA modification method that(More)
The two domains of the hairpin ribozyme-substrate complex, usually depicted as straight structural elements, must interact with one another in order to form an active conformation. Little is known about the internal geometry of the individual domains in an active docked complex. Using various crosslinking and structural approaches in conjunction with(More)
To form a catalytically active complex, the essential nucleotides of the hairpin ribozyme, embedded within the internal loops of the two domains, must interact with one another. Little is known about the nature of these essential interdomain interactions. In the work presented here, we have used recent topographical constraints and other biochemical data in(More)
In sequencing a 2200 bp region of the Neurospora crassa mitochondrial DNA encoding the 3' end of the large rRNA gene and a cluster of six tRNA genes, we have found that the tRNA genes are flanked by highly conserved GC-rich palindromic DNA sequences. An 18 bp long core sequence, 5'-CC CTGCAG TA CTGCAG GG-3', containing two closely spaced Pst I sites, is(More)
Sequence analysis of 5'-[32P] labeled tRNA and eukaryotic mRNA using an adaptation of a method recently described by Donis-Keller, Maxam and Gilbert for mapping guanines, adenines and pyrimidines from the 5'-end of an RNA is described. In addition, a technique utilizing two-dimensional polyacrylamide gel electrophoresis for identification of pyrimidines(More)
Through analysis of cloned fragments of N. crassa mitochondrial DNA, we have derived a physical map for the region of the mitochondrial genome which encodes the ribosomal RNAs and most of the tRNAs. We have located RNA genes on this map by hybridization of purified 32P end-labeled RNA probes, and our findings are as follows. First, the gene for the large(More)
The nucleotide sequence of cytoplasmic phenylalanine tRNA from Euglena gracilis has been elucidated using procedures described previously for the corresponding chloroplastic tRNA [Cell, 9, 717 (1976)]. The sequence is: pG-C-C-G-A-C-U-U-A-m(2)G-C-U-Cm-A-G-D-D-G-G-G-A-G-A-G-C-m(2)2G-psi-psi-A-G-A-Cm(More)
Physician interest in global health, particularly among family physicians, is reflected by an increasing proliferation of field training and service experiences. However, translating initial training involvement into a defined and sustainable global health career remains difficult and beset by numerous barriers. Existing global health literature has largely(More)
We have isolated and characterized a Neurospora crassa gene homologous to the yeast CYH2 gene encoding L29, a cycloheximide sensitivity-conferring protein of the cytoplasmic ribosome. The cloned Neurospora gene was isolated by cross-hybridization to CYH2. It was sequenced from both cDNA and genomic clones. The coding region is interrupted by seven(More)
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