**44. Beta-glucosidase**

**41. Cysteine proteinase**

Relationships

252

**42. Isoflavone synthase**

complished extensive hydrolysis of beta-conglycinin [45].

against pathogens and signal molecules to symbiotic bacteria [46].

**43. UDP-glucose:Flavonoid 3-O-glucosyltransferase**

Two cDNAs, were isolated from the cotyledons of growing soybean seedlings by cDNA rep‐ resentational difference analysis (cDNA RDA) and rapid amplification of cDNA ends (RACE). Both CysP1 and CysP2 encode a cysteine proteinase (CPR) with a C-terminal KDEL motif. CysP1 and CysP2 were expressed from 6 days to 13 or 14 days after germination in the cotyledons of growing seedlings and in the root, flower and pod of soybean plants [44]. Two types of cysteine proteases, low-specificity enzymes from the papain family and Asnspecific enzymes from the legumin family, are endopeptidases that play a role in the degra‐ dation of seed storage proteins during early growth of seedlings. The action of the enzymes (CPPh1 and LLP, respectively) from the common bean *(Phaseolus vulgaris L.*) on the common bean storage protein phaseolin, and on the homologous soybean storage protein beta-con‐ glycinin, has been examined. The two most active proteinases detected in common bean seedlings individually cannot bring about extensive degradation of phaseolin. However, the successive action of LLP and CPPh1 leads to extensive hydrolysis of phaseolin. CPPh1 ac‐

A Comprehensive Survey of International Soybean Research - Genetics, Physiology, Agronomy and Nitrogen

Isoflavonoids are secondary metabolites important in nodulation and defense responses. They have a common occurrence in leguminous plants. Isoflavone synthase (IFS) catalyzes the key entry point step of isoflavone biosynthesis from the general phenylpropanoid path‐ way. IFS transcripts were detected in seeds and roots. The transcript levels of the isoforms IFS1 and IFS2 are altered in response to *Bradyrhizobium japonicum* or salicylic acid. The ex‐ pression pattern of IFS1 in soybean is indicative of the roles of isoflavonoids in defense

The seed coats of black soybean accumulate red (cyanidin-based), orange (pelargonidinbased) blue (delphinidin-based), purple (petunidin-based), and anthocyanins almost exclu‐ sively as 3-O-glucosidesThe full-length cDNA encoding UDP-glucose:flavonoid 3-Oglucosyltransferase (UGT78K1), the enzyme which catalyzes the last step in anthocyanin biosynthesis, was isolated from black soybean seed coat using rapid amplification of cDNA ends (RACE). The recombinant enzyme glucosylated only anthocyanidins and flavonols with 3-OH regiospecificity. Galactose could also be transferred, albeit with relatively low ac‐ tivity, to the 3-position of cyanidin or delphinidin *in vitro*. The results are consistent with the presence of mainly 3-O-glucosylated and minor amounts of 3-O-galactosylated anthocya‐ nins in the black soybean seed coat. The recombinant enzyme exhibited pronounced sub‐ strate inhibition by cyanidin at 100 M acceptor concentration. The accumulation of

A novel 75-kDa beta-glucosidase with strict specificity toward glucosyl isoflavones but not malonylglucosidic conjugates of soybean isoflavones, was isolated from soybean. Its N-ter‐ minal amino acid sequence EYLKYKDPKA closely resembled those of maize and wheat gly‐ cosidases. Its optimal temperature and pH were 45 degrees C and 4.5, respectively. It was completely inhibited by 1 mM Hg2+ or 10 mM Al3+ ion, and glucose and mannose also affect‐ ed the activity [48].
