The amino acid sequence of hamster pancreatic ribonuclease

Molecular paleoscience: systems biology from the past

Experimental paleomolecular biology, paleobiochemistry, and paleogenetics are closely related emerging fields that infer the sequences of ancient genes and proteins from now-extinct organisms, and then resurrect them for study in the laboratory. The goal of paleogenetics is to use information from natural history to solve the conundrum of modern genomics: How can we understand deeply the function of biomolecular structures uncovered and described by modern chemical biology? Reviewed here are the first 20 cases where biomolecular resurrections have been achieved. These show how paleogenetics can lead to an understanding of the function of biomolecules, analyze changing function, and put meaning to genomic sequences, all in ways that are not possible with traditional molecular biological studies.

The amino acid sequence of human pancreatic ribonuclease

The primary structure of human (Homo sapiens) pancreatic ribonuclease has been determined by automatic sequencing of the native protein and by analysis of peptides obtained by cleavage with proteolytic enzymes, cyanogen bromide, and hydroxylamine. The following sequence was deduced: (sequence in text). Human pancreatic ribonuclease differs at 37 positions from bovine pancreatic ribonuclease. In addition the human enzyme has three more residues at the C-terminus. About half of the enzyme molecules contain carbohydrate attached to the sequence Asn-Met-Thr (34-36). Two other Asn-X-Ser/Thr sequences are carbohydrate free. Human pancreatic ribonuclease contains many positively charged residues, especially near the N-terminus, while negatively charged residues are more concentrated near the C-terminus.

Rat pancreatic ribonuclease: agreement between the corrected amino acid sequence and the sequence derived from its messenger RNA

A corrected amino acid sequence of rat pancreatic ribonuclease is presented which is in agreement with the messenger RNA sequence in [J. Biol. Chem. (1982) 257, 14582-14585]. The corrections do not change the general position of rat ribonuclease in trees which can be constructed for ribonuclease sequences, although they do place the rat sequence somewhat closer to the mouse sequence. The evolutionary rate of ribonuclease in the rodent family of the Muridae (rat and mouse) now has been calculated to be 140 nucleotide substitutions per 10(8) years per 100 codons, and still is one of the highest rates yet observed. The occurrence of 4 additional amino acids at the C-terminus in several mammalian ribonucleases is in agreement with the position of a second stop codon in the 3' non-coding region of the rat messenger RNA sequence.

Origin of the duplicated ribonuclease gene in guinea-pig: comparison of the amino acid sequences with those of two close relatives: capybara and cuis ribonuclease

The amino acid sequences of the pancreatic ribonuclease from capybara (Hydrochoerus hydrochaeris) and cuis (Galea musteloides) were determined. Both species belong to the same superfamily of the hystricomorph rodents as the guinea-pig. In guinea-pig pancreas two ribonucleases are present as a result of a recent gene duplication, but in capybara and cuis pancreas only one single ribonuclease has been found. A most parsimonious tree of ribonucleases indicates that the gene duplication leading to both guinea-pig ribonucleases occurred before the divergence of guinea-pig from capybara and cuis. This would mean that changes in expression of the ribonuclease genes have occurred in these taxa. Cuis and capybara ribonuclease have no Asn-X-Ser/Thr sequences and are carbohydrate-free proteins. Capybara ribonuclease has leucine at position 114, a position occupied by proline in the cis-configuration in bovine pancreatic ribonuclease.

The primary structures of pancreatic ribonucleases from African porcupine and casiragua, two hystricomorph rodent species

The amino acid sequences of the pancreatic ribonucleases from African porcupine (Hystrix cristata) and casiragua (Proechimys guairae, a caviomorph rodent species related to the coypu) were determined. The ribonucleases were isolated form minces of pancreatic tissue which had been used for the extraction of the insulins. The results of the sequence determinations of residues 67-78 in both enzymes were ambiguous. Therefore, homology with other ribonucleases has been used in deriving these sequences. At position 94 aspartic acid was found, while all other ribonuclease sequenced to date have asparagine at this position. This may indicate a specific deamidation as a result of the acidic conditions during the extraction of insulin. The amino acid sequence of African porcupine ribonuclease shows a close relationship with those of the South-American caviomorph rodents, which implies that the hystricomorph suborder of the rodents, to which both the African porcupine and the caviomorphs belong, is a natural (evolutionary) taxon. Both porcupine and casiragua ribonuclease are glycoproteins with complex-type carbohydrate chains attached to asparagine-34.

Nucleic acid-protein interactions. Degradation of double-stranded RNA by glycosylated ribonucleases

1. Extensively glycosylated ribonucleases, like the enzymes from pig and horse pancreas, show a much higher activity on double-stranded RNAs than similarly charged, carbohydrate-free RNAases under stranded assay conditions (relatively high salt concentrations). Glycosylated pig and horse pancreas RNAases also show a larger destabilizing effect on double-stranded poly[d(A-T)] X poly[d(A-T)], than that displayed by bovine RNAase A under these conditions. Both activities show a similar dependence on the ionic strength of the medium. 2. A partial enzymic removal of the heterosaccharide side chains from pig and horse RNAases reduces but their degradative activity on double-stranded RNA and their destabilizing action on poly[d(A-T)] X poly[d(A-T)]. 3. These results are tentatively correlated with a modification of the microenvironment of the enzyme protein caused by its extensive glycosylation.