Hydrolysis of RNA to 5′‐nucleotide by seed sprouts, particularly malt sprouts

Abstract

SummaryConditions for the efficient conversion of commercial RNA to nucleoside 5'-monophosphate by means of a phosphodiesterase in malt sprouts have been determined. A comparison of the enzyme content of the rootlets, stems, and kernels of various plant seedlings, including barley, rye, oat, wheat, rice, and beans shows maximum amounts in the rootlets, and minimum quantities in the ungerminated kernels. Of all the seedlings tested, (mung bean, soy bean, oat, wheat, rice, barley) barley gave the highest conversion of RNA to 5'-nucleotides. Commercial malt sprouts prepared from 6 different malted barleys including 2-rowed and 6-rowed amples all showed about the same amount of phosphodiesterase content. Be des phosphodiesterase, other enzymes capable of hydrolyzing KNA and 5'-nucleotides were found in sprouts. These included 3'-phosphodiesterases, 5'-nucleotidases, and nucleosidases. By carefully pretreating both extracts and the solid sprouts at elevated temperatures for a limited time and by the addition of minimum amounts of k + 2 , the action of these undesirable enzymes was either effectively destroyed or minimized so that the production of 5'-nucleotides was maximized. I t was found that suspensions of appropriately washed and treated barley malt rootlets are substantially more effective than aqueous extracts for converting RNA to Z'-nucleotides.

A novel multi-biofunctional protein from brown rice hydrolysed by endo/endo-exoproteases

“…25 The results showed that the MSG, 5′-GMP and 5′-IMP components identified by HPLC were found in eb-RPH and ep-RPH (Fig. 26 The proteolytic process could break down these nucleotides that are bound to the proteins, resulting in the release of non-volatile flavor compounds. The MSG, 5′-GMP and 5′-IMP found in the two RPHs could be naturally synthesized and are present in brown rice.…”

“…The MSG, 5′-GMP and 5′-IMP found in the two RPHs could be naturally synthesized and are present in brown rice. 26 The proteolytic process could break down these nucleotides that are bound to the proteins, resulting in the release of non-volatile flavor compounds. Therefore, the MSG, 5′-GMP and 5′-IMP contents in ep-RPH were higher than those in eb-RPH because of the high hydrolysis efficiency of PROTEASE FP51®.…”

Rootlets, a Malting By-Product with Great Potential

“…5 -phosphodiesterase (5 PDE) has been the predominant enzyme isolated and utilised in applications from barley rootlets. It has been found in appreciable amounts in the barley rootlets and in the malted barley grain [71,72]. The enzyme has been used commercially to hydrolyse RNA to make 5 -nucleotides.…”

“…Processes for the extraction of 5 PDE from barley rootlets vary, with some patents (Table 4) also developed. The process generally requires a purification step, because various other undesired enzymes such as phosphatases, 5 -nucleotidase and nucleosidases may also be present in barley rootlets [71,78] that may produce unwanted products or inhibit 5 -nucleotide yield.…”

<b>A reversed phase HPLC method for the analysis of nucleotides to determine 5’-PDE enzyme activity</b>

“…Reported enzymes extracted from barley roots included DNase, RNase, 5'-adenosine monophosphatase, 3'-uridine monophophatase, and other nucleases [7,9,10]. Laufer and Gutcho [11] reported that 5'-nucleotides, 3'-nucleotides, phosphoric acid and nitrogenous bases were found in the enzymatic hydrolysis products of yeast RNA by enzymes from barley roots. As we know, the main hydrolysis products of yeast RNA catalyzed by 5'-PDE are 5'-nucleotides, mainly 5'-CMP, 5'-UMP, 5'-GMP and 5'-AMP, it is more reasonable to appraise the enzyme activity of 5'-PDE by measuring the amount of the four 5'-nucleotides in the hydrolysis reaction, to detect a more reliable and precise enzyme activity.…”