A & M U 0.430 X C WWW sapling learning.com /ibiscms/mod/ibis/view.php?id-1973899
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A & M U 0.430 X C WWW sapling learning.com /ibiscms/mod/ibis/view.php?id-1973899 O Not set A 73.3/100 9/9/2015 11:35 AM Gradebook Attempts Score Pr dic Tab Questi 25 of 27 Map e criteria for acceptable biological and biochemical buffers were established by studies conducted by Norman Good et al. in 1966. These criteria included a pKa within physiological range solubility in water membrane impermeability minimal salt effect or ion interactions minimal temperature and concentration effects on dissociation chemical stability .no/minimal, or well-documented, UV light absorbance at certain wavelengths easy to prepare Choose the buffer characteristic, if any, that fails to meet the criteria. Choose the best answer listed 20 HEPES pKa at 25 oC 7.48 Phosphate buffer pK2 at 25 c 7.200 ApKa C 0.014 APKaloC 0.0028 may interfere with a type of protein assay may react with calcium or low absorbance in UV range magnesium salts 95 may inhibit some enzymes ineffective buffer near 23 physiological pH ffective buffer n physiological pH minimal solubility in water O minimal solubility in water 24 O soluble in nonpolar solvents influence of temperature on down dissociation is too high unknown UV light absorbance to see a 25 options O interactions with cations O none of the above none of the above 26 95 Next Give Up & Vi Ch US 27 pyright 20 2015 Sapling Le 90 tact a Search the web and Windows Assignment Information Available From: 8/24/2015 06:00 PM Due Date: Set Points Possible 100 Grade Category: Graded Description: Policies Homework heck y plete up on any question keep trying h q gh get 5% ct att O eTextbook O Help With This Topic O Web Help & Videos O Technical Support and Bug Reports 4:32 AM 9/12/2015Explanation / Answer
Phosphate buffer fails to meet criteria because,
Its interactions with cations. The buffer and cations react, buffer becomes less effective because it cannot handle additional hydrogen ions. If a complex forms between the buffer and a cofactor, say a metal cation like zinc or magnesium, reaction also might be compromised.
Minimal solubility in water Biological reactions, for the most part, occur in aqueous environments, and the buffer should be water-soluble.
Hepes buffer fails to meet criteria because
Its solubility in non-polar solvents: Buffers should have low solubility in non-polar solvents (fats, oils, and organic solvents), as this would tend to prevent the buffer compound from accumulating in non-polar compartments in biological systems: cell membranes and other cell compartments.
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