Abstract: By employing the ah initio gauge invariant atomic orbital (GIAO) approach, the influence of hydrogen bonding on the ¹³C chemical shift tensor in solid tyrosine was studied. Comparisons of the values of the present paper with those previously calculated and with the experimental results were made. The root-mean-square (rms) error found by comparing the predicted (without hydrogen bonding interaction) and the observed prindpal component for the carboxyl carbon of tyrosine was 33.4ppm; whereas when the hydrogen bonding interaction was introduced, the relevant rms error would be reduced to 23ppm. This dearly highlihts the importance of considering the hydrogen bonding interaction in the study of the ¹³C chemical shieldings for the carboxyl carbons, espedally for the δ₂₂ component, the results presented in this paper also agreed with the observed results of McDermott et al.

Key words: Tyrsine, Chemical shielding tensor, Gauge invariant atomic orbital, Hydrogen bonding interaction