Joachim Ludwig Weickmann

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.

Primer-directed mutagenesis of linearized plasmids☆

Two novel mutagenesis techniques to specifically alter the sequence of plasmid DNA have been developed. In contrast to other primer-directed mutagenesis methods which require a single-stranded, closed-circular template, a linearized single strand was used as the mutagenesis template. The template is prepared by restriction enzyme digestion of covalently-closed-circular plasmid DNA. These methods are simple, require small amounts of plasmid DNA, and can result in a relatively high frequency of mutagenesis.

Immunological Assay of Serum Ribonuclease as a Marker for Pancreatic Cancer

Abstract Antibodies to human pancreatic ribonuclease were used to quantitate pancreatic-like enzyme in the serum of patients with pancreatic and other types of cancer, as well as healthy volunteers and individuals with diseases other than cancer. Serum RNase levels are normally age and sex related. In cancer patients the RNase level is frequently above the expected value, but not always so; pancreatic cancer patients showed elevated RNase in about half of our cases. But kidney and bladder cancer patients almost always showed elevated serum RNase, and non-cancerous kidney diseases also resulted in high enzyme levels. We conclude that serum pancreatic-like RNase is a poor marker for pancreatic cancer or any other specific disease, but its level may be a sensitive measure of kidney function.