Hans-Joachim Fritz

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The Archaeon Methanosarcina mazei and related species are of great ecological importance as they are the only organisms fermenting acetate, methylamines and methanol to methane, carbon dioxide and ammonia (in case of methylamines). Since acetate is the precursor of 60% of the methane produced on earth these organisms contribute significantly to the(More)
The efficiency of methyl-directed DNA mismatch-repair of E. coli acting in vivo on heteroduplex genomes of phage M13 was found to be strongly dependent on the nature of the base/base mismatch to be corrected. Three efficiency classes were characterized:high (T/G, C/A and G/G); intermediate (A/A); and low (G/A, A/G, T/T, C/C, C/T and T/C). Methyl-directed(More)
Human tryptase, a mast-cell-specific serine proteinase that may be involved in causing asthma and other allergic and inflammatory disorders, is unique in two respects: it is enzymatically active only as a heparin-stabilized tetramer, and it is resistant to all known endogenous proteinase inhibitors. The 3-A crystal structure of human beta-tryptase in a(More)
In Escherichia coli K-12, the Dcm methyltransferase catalyses methylation of the inner cytosine residue in the sequence CCA/TGG. Hydrolytic deamination of 5-methylcytosine bases in DNA leads to thymine residues, and hence to T/G mismatches, pre-mutagenic DNA lesions consisting of two natural DNA constituents and thus devoid of an obvious marker of the(More)
The genome of Methanothermobacter thermautotrophicus, as a hitherto unique case, is apparently devoid of genes coding for general uracil DNA glycosylases, the universal mediators of base excision repair following hydrolytic deamination of DNA cytosine residues. We have now identified protein Mth212, a member of the ExoIII family of nucleases, as a possible(More)
IS-elements are devoid of easily recognizable transacting functions and exert their visible effects in the position cis only (recent reviews Calos and Miller 1980; Starlinger 1980). It has been a matter of debate, whether these elements encode functions for their own transposition. In the case of the E. coli IS-elements this could not easily be determined(More)
No genes for any of the known uracil DNA glycosylases of the UDG superfamily are present in the genome of Methanothermobacter thermautotrophicus DeltaH, making it difficult to imagine how DNA-U repair might be initiated in this organism. Recently, Mth212, the ExoIII homologue of M. thermautotrophicus DeltaH has been characterized as a DNA uridine(More)
Herpes B virus (or Herpesvirus simiae or Macacine herpesvirus 1) is endemic in many populations of macaques, both in the wild and in captivity. The virus elicits only mild clinical symptoms (if any) in monkeys, but can be transmitted by various routes, most commonly via bites, to humans where it causes viral encephalitis with a high mortality rate. Hence,(More)
The mutagenic threat of hydrolytic DNA cytosine deamination is met mostly by uracil DNA glycosylases (UDG) initiating base excision repair. However, several sequenced genomes of archaeal organisms are devoid of genes coding for homologues of the otherwise ubiquitous UDG superfamily of proteins. Previously, two possible solutions to this problem were offered(More)
A novel mutagenesis/gene expression and protein purification scheme was established for ready construction and purification of variant immunoglobulin domains in Escherichia coli. This procedure, which has been applied to the production of the VK domain of the Bence-Jones protein REI and structural variants of it, rests on the synthesis of chimeric proteins(More)