In plants, starch is the main carbohydrate reserve and an important ingredient in human nutrition. Nutritionally, starch is classified into rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) based on the rate and degree of digestion. RS escapes enzymatic digestion in the small intestine, but in the large intestine microbial flora may ferment some RS. Malic acid is C4 carboxylic acid with two carboxyl groups. It is well known to take from 69% up to 92% of all organic acids in grape berries and leaves and is naturally produced by many organisms without showing any nutritional harm. However, properties of malic acid treated starch has not been clearly reported. The objectives of this study were to investigate the influence of pH value on low-digestible malate starch formation and digestibility in relation to structural properties of corn starch. Different pH values (1.5-8.5) of 2 M malic acid solution were reacted with corn starch in a forced-air oven at temperature of 130°C for 12 hr. Using FT-IR, carbonyl groups were detected in malate starch, indicating the formation of cross-linking by esterification. Increasing pH value of malic acid-treated sample from 1.5 to 8.5 showed an increase in degree of substitution (DS) and resulted in increase in the RS content from 18.2 to 74.8%, which was maintained after gelatinization. The granular structure of malate starches was not destroyed, and the starches maintained birefringence. This malate starch could be utilized in heat processed foods such as bread and cookies as well as in the products with reduced calories.

An in vitro study was conducted to investigate the effect of propionate precursor (malate or fumarate) on fermentation characteristics, production of conjugated linoleic acid (CLA) and methane (CH₄) by rumen microbes when incubated with linoleic acid (C18:2) as a CLA precursor. Total CH₄ production for 12h incubation, however, was greatly reduced (P＜0.0001) by all the supplements compared to that of control, and its production from M-LA or F-LA treatment was smaller than that from LA treatment. Supplementation of M-LA or F-LA also increased concentrations of cis9, trans11-CLA (P＜0.039 - P＜0.001) for all incubation times and trans10,cis 12-CLA at 1h (P＜0.013), 3h(P＜0.036) and 12h (P＜0.025) incubation times compared to LA supplementation.

온도, pH및 염도 stress가 굴(Crassostrea gigas)의 malate dehydrogenase isozyme에 미치는 영향을 전기영동법으로 분석하였다. 대조군의 MDH isozyme은 2개의 band가 양극 쪽으로 이동되어 분리되었다. 각 실험 온도와 pH를 12시간 노출시킨 실험군에서는 1개의 band만 양극 쪽에서 분리되었고, 24시간과 48시간 노출한 실험군에서는 2개의 band가 모두 양극 쪽에서 분리되었다. 염분 농도가 5ppt

암컷 Aedes aegypti의 난성숙과장에서 새로 나타나는 malate dehydrogenase(L-malate, oxidoreductase, EC 1.11.37, MDH)를 DEAE-Sepharose, Sulphonyl-Sepharose, Cibacron 3FGA affinity chromatography를 이용하여 분리정제하여 그 특성을 조사하였다. 분자량은 70,000 dalton정도의 dimer 형태로 되어 있으며 최적 pH는 malate-oxaloacetate반응에서는 pH 9.0~9.2, oxaloacetate-malate 반응에서는 pH 9.8~10.2이었다. 정재된 MDH는 mitochondria에 위치하고 있으며 기질로서 malate에 대한 Km값의 경우 M, oxaloacetate에 대한 Km 값은 M, NAD에 대한 Km값은 M이며 NADH에 대한 Km 값은 M 을 보이고 있으며 각각의 기질에 의한 저해현상을 보이고 있었다. 기질에 대한 Km값을 부분적으로 분리한 DEAE-sepharose에 흡착된 원형질 MDH와 비교한 결과 malate에 대한 Km 이 으로 상당한 차이를 보이고 있었다. 또한 정제된 MDH는 cltrate, -ketoglutarate, ATP 등의 대사산물에 의하여 저해작용을 받았다. ATP 및 citrate에 의한 MDH 활성도 저해는 oxaloacetate-malate반응에서 보다는 malate-oxaloacetate 반응에서 덜 일어났다. Oxaloacetate-malate 반응의 경우 ATP에 의하여저해작용이 완전히 일어났으며 malate-oxaloacetate반응에서는 cltrate에 의하여 저해작용이 일어나지 않았다. 흡혈 후 생성되는 MDH는 난소에서 합성되며 흡혈 수 난소에서 18시간 때부터 활성도가 나타나 48시간 이후 최고 활성도가 유지되는데 TCA회로의 isocitrate dehydrogenase 의 경우 난소내에서의 활성도 변화가 MDH의 변화 양상과 같았다.

Malate dehydrogenase is a ubiquitous enzyme in plants, involving in a range of metabolic processes depending on its subcellular location. A malate dehydrogenase (PgMDH) cDNA was isolated and characterized from the root of Panax ginseng C. A. Meyer. The deduced amino acid sequence of PgMDH showed high similarity with the NAD-dependent mitochondrial malate dehydrogenase from Glycinemax (P17783), Eucalyptus gunnii (P46487), and Lycopersicon esculentum (AAU29198). And the segment of a malate dehydrogenase gene was amplified through RT-PCR. The expression of PgMDH was increased after treatments of chilling, salt, UV, cadmium or copper treatment.

생쥐의 난자는 특별한 첨가물이나 난구세포 없이 체외 배양해도 성숙율이 높은 반면 돼지 난자의 체외성숙율은 매우 낮다. 본 연구는 이러한 차이의 원인을 연구하기 위하여 생쥐와 돼지 난자의 에너지 생성에 관여하는 유전자인 malate dehydrogenase(Mor2)의 기능을 RNAi를 이용하여 비교 분석하였다. 생쥐와 돼지 각각의 Mor2 double-stranded RNA(dsRNA)를 제작하고, 생쥐는 난구세포를 제거한 미성숙(GV) 난자의 세포질에