Variations in Enzyme Activities during Arabidopsis Leaf Growth

Variations in Enzyme Activities during Arabidopsis Leaf Growth

Activities of various enzymes were measured and compared in the growing leaves of Arabidopsis tlnliann. Phenylalanine ammonia-lyase activity is maximal in the leaves of 2-week-grown Arabidopsis. Tyrosine ammonia-lyase activity is maximal in the leaves of 3-week-grown and 4-week-grown Arabidopsis. Activity of thioltransferase, an enzyme involved in the reduction of various disulfide compounds, is higher in younger leaves than in older ones. A similar pattern was obtained in the activity of thiordoxin, a small protein known as a cofactor of ribonucleotide reductase and a regulator of photosynthesis. Activity of glutathione reductase is also higher in the younger leaves. Malate dehydrogenase activity remains relatively constant during the growth of Arabidopsis leaves. The results offer preliminary informations for further approach to elucidate mechanism on growth-dependent variations of these enzymes.