Abstract
Changes of contents of reducing sugar and sucrose and activities of sucrose-phosphate synthase, sucrose synthease and invertase from the leaves of barley (Hordeum vulgare L. cv. Chalssal) seedlings grown at $4^{\circ}C$ were investigated, and the property of acid invertase were also examined. In the seedlings grown at $4^{\circ}C$ for 3 days, the contents of reducing sugar and sucrose were increased to 1.3 and 2.4 times, respectively. Activity of acid invertase was decreased markedly by cold treatment while the activities of sucrosephosphate synthase, sucrose synthase, and alkaline invertase were not changed. In acid phosphatase purified partially by ammonium sulfate fractionation and DEAE-Sephacel column chromatography, the $K_m$ value for sucrose was 9.5 mM and the optimum pH and temperature was 5.5 and $35^{\circ}C$ respectively. This enzyme was supposed to be ${\beta}-fructosidase$ by studies on the substrate specificity and the molecular weight was estimated to be 63 Kd by Sephadex G-200 gel chromatography.graphy.
저온처리($4^{\circ}C$)하에서 보리(Hordeum vulgare L. cv. Chalssal) 유식물 잎의 당함량과 sucrosephosphate synthase, sucrose synthease, invertase의 활성의 변화를 측정하고, 또한 acid invertase의 성질을 조사하였다. 저온처리 3일만에 보리유식물의 환원당과 설탕의 함량은 1.3배 및 2.4배로 각각 증가하였다. 그리고 sucrosephosphate synthase, sucrose synthase 및 alkaline invertase의 활성에는 별다른 변화가 없었으나 acid invertase의 활성은 크게 저하하였다. Ammonium sulfate 분획과 DEAE-Sephacel 컬럼으로 부분정제한 acid invertase에서, 설탕에 대한 Km은 9.5mM이고 최적 pH는 5.5, 최적온도는 $35^{\circ}C$로 측정되었다. 여러 가지 기질에 대한 특이성을 조사한 결과 본 효소는 ${\beta}-fructosidase로$ 추정할 수 있었으며, 효소의 분자량은 Sephadex G-200 컬럼 크로마토그래피로 산출하였을 때 63 Kd이었다.