I have given the protocol for the cyclodextrin glygosyl
transferase assay:
One ml of appropriately diluted enzyme sample was incubated
at 60 °C for 15 min with 5 ml of 1% (w/v) gelatinized
soluble starch in 50 mM, 7.0-pH Tris–HCl buffer. Reaction
was terminated by boiling the reaction mixture for 3 min
and reaction volume was made to 10 ml with distilled water.
Two ml of above reaction mixture was withdrawn and mixed
with 3 ml of Tris–HCl buffer, 5 ml of 125 mM Na2CO3, and
0.5 ml of phenolphthalein (25 mg phenolphthalein/100 ml
absolute alcohol). Absorbance was measured at 550 nm. The
percent decrease of sample was calculated with respect to
control containing 5 ml of buffer, 5 ml of sodium carbonate
and 0.5 ml of phenolphthalein.
where Acontrol = absorbance of control and Atest =
absorbance of sample.
The amount of β-cyclodextrin (β-CD) produced was estimated
from the standard graph of 0–500 μg/ml β-CD concentration
against % decrease in absorbance. One unit of CGTase was
defined as the amount of enzyme required to produce 1 μm of
β-CD/min.
Please can you suggest me the formula for the defination
given in the last line
DNA binding by proteins with the helix-turn-helix (HTH)
motif does not involve
a) altered stacking of the DNA at the center of symmetry.
b) hydrogen bonds, salt bridges, and van der Waals contacts.
c) interactions with base pairs in the major groove of DNA.
d) interactions with the sugar-phosphate backbone of DNA.
65
Which vitamins participate, in coenzyme form, in reactions
of the tricarboxylic acid cycle?
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