1. Department of Biochemistry, University College, Galway, Ireland
2. Institut für Holzchemie, D-2050 Hamburg 80, Germany
3. Laboratorium voor Biochimie, Rijksuniversiteit Gent, B-9000 Gent, Belgium
4. 1nstitute of Chemistry, Slovak Academy of Sciences, 842 38 Bratislava, Czechoslovakia