Abstract: A process for the simultaneous enzymatic synthesis of a mixture of alkyl esters of peptides and peptides is presented. In the process, a protein substrate and at least one aliphatic alkanol having from 1 to 5 carbon atoms at a concentration of more than about 30% V/V, preferably 70% V/V to 90% V/V, are treated with a serine protease. A mixture of alkyl esters of peptides and peptides having an esterification value of at least 25% and an average molecular mass of about 3,000 to about 10,000 daltons is recovered. In a further step, the mixture of alkyl esters of peptides and peptides may be precipitated from an alcoholic medium, in an aqueous phase to prepare microparticles. The mixture of alkyl esters of peptides and peptides, or the microparticles may be used in cosmetic, food, pharmaceutical, wetting agent, film-agent, or emollient compositions.

Abstract: The invention relates to the preparation of water-soluble L-tyrosine derivatives having the formula ##STR1## where R.sub.1 is a L-malyl, L-lactyl, L-glutamyl or L-aspartyl group, R.sub.2 is a --OH, --OM, methoxy, ethoxy or amino group and M is an alkaline metal, by enzymatic condensation of an acid selected among L-malic, L-lactic, L-glutamic and L-aspartic acids, with a L-tyrosine derivatives selected among the ethyl and methyl esters and the amide of L-tyrosine. The enzyme is obtained from a culture of Micrococcus casealyticus. The compounds where R.sub.1 is a L-malyl or L-lactyl group are new. Said L-tyrosine derivatives are useful in cosmetic and pharmaceutical compositions, such as tanning and sun compositions.