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产品货号：ZZK-K-BETA3
产品品名：β-淀粉酶检测试剂盒
英文品名：β-Amylase (Betamyl-3 method) Assay Kit
规格型号： 100/200 assays per kit
For the specific measurement of beta-amylase in malt flour.
INTRODUCTION:
β-Amylase plays a central role in the complete degradation of starch to
metabolisable or fermentable sugars during the germination or malting
of cereal grains. It also finds considerable application, together with
starch debranching enzymes, in the production of high maltose syrups.
β-Amylase is usually measured using non-specific reducing sugar assays
with starch as substrate. In some methods, the α-amylase is first
inactivated by treatment at low pH.
A major advance in the assay of β-amylase was introduced by
Mathewson and Seabourn1 who found that the Calbiochem Pantrak?
serum α-amylase reagent could be used to measure β-amylase in the
presence of cereal α-amylase. The reagent (Pantrak) consists of a
mixture of p-nitrophenyl-α-D-maltopentaoside (PNPG5) and
p-nitrophenyl-α-D-maltohexaoside (PNPG6). These substrates are
rapidly hydrolysed by β-amylase, but are only slowly cleaved by cereal
α-amylase, which requires a longer stretch of α-1,4-linked D-glucosyl
residues to satisfy the substrate sub-site binding requirements.
Subsequently, Megazyme offered a product, Betamyl? (β-Amylase
Assay Reagent) that comprised just PNPG5 and α-glucosidase2,
which gave greater specificity. This reagent is now superceded by
the Megazyme Betamyl-3?, β-Amylase assay reagent, which is more
specific and considerably more stable than the Betamyl? reagent.
The Megazyme Betamyl-3?, β-amylase test reagent employs high
purity β-glucosidase and p-nitrophenyl-β-D-maltotrioside (PNPβ-G3).
The level of β-glucosidase used ensures maximum sensitivity of the
assay. On hydrolysis of PNPβ-G3 to maltose and p-nitrophenyl-β-Dglucose
by β-amylase, the p-nitrophenyl-β-D-glucose is immediately
cleaved to D-glucose and free p-nitrophenol by the β-glucosidase
present in the substrate mixture (Scheme 1). Thus, the rate of release
of p-nitrophenol relates directly to the rate of release of maltose
by β-amylase. The reaction is stopped, and the phenolate colour is
developed, on addition of a high pH Trizma base solution.
The PNPβ-G3 plus β-glucosidase mixture contains stabilisers which
significantly increase its stability. The blank absorbance value of the
Betamyl-3? substrate solution, when stored at 4 or 20°C, increases
much more slowly than similar increases for Betamyl?. reagent
KITS:
Kits suitable for performing 100 assays are available from Megazyme.
The kits contain the full assay method plus:
Bottle 1: (x2) Each vial contains p-nitrophenyl-β-D-maltotrioside
(PNPβ-G3) plus β-glucosidase (50 U) and stabilisers.
Stable for 大于 4 years at -20°C.
Bottle 2: Tris/HCl buffer (25 mL, 1 M, pH 8.0) plus disodium
EDTA (20 mM) and sodium azide (0.02 % w/v).
Stable for approx. 4 years at 4°C.
Bottle 3: MES buffer (48 mL, 1 M, pH 6.2) plus disodium
EDTA (20 mM), BSA 10 mg/mL and sodium azide
(0.20 % w/v).
Stable for approx. 4 years at 4°C.
Bottle 4: Cysteine hydrochloride (16 g).
Stable for 大于 2 years at room temperature.
Bottle 5: Malt flour of standardised β-amylase activity (as
specified on bottle label).
Stable for 大于 4 years at room temperature.
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文章号：=2278JP2278
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