Protein Testing Comparison
The common testing methods for protein are:
1. ASTM D5712–95 and 99
2. RRIM Modified Lowry
3. EN455 Part 3–94 and 00
4. ISO/DIS 12243
Major differences between the methods:
| # | Procedure |
ASTM |
RRIM |
EN455 |
ISO |
| 1 | Extraction | 1 glove peripheral cut in PBS (0.025 M, pH 7.4) at 25C for 2 hr | Cut pieces in PBS (0.01M, pH 7.4) at 23C for 3 hr | 2 gloves (glove in glove), TES (0.1M, pH 7.4) at 25C for 2 hr | Cut pieces in PBS (0.01M, pH7.4) at 25C for 2 hr |
| 2 | Precipitation Redissolution/ concentration |
Using DOC 0.15%, TCA 72%, PTA 2% 0.35 – 1 ml of 0.20 M NaOH |
Using TCA 35% and PTA 1.6% 1-6 ml of 0.2 M NaOH |
Using DOC 0.15%, TCA 72%, PTA 72% 0.20-1 ml of 0.10M NaOH |
Using DOC 0.15%, TCA 72%, PTA 72% 0.80-4.0 ml of 0.20M NaOH |
| 3 | Lowry microassay Color development Calibration Standard |
Using alkaline copper tartrate & Folin 50% 15 + 30 min Ovalbumin solution |
Using alkaline copper citrate & Folin 72% 10 + 30 min BSA solutions |
Bio-Rad DC protein assay kit 1 30 min Ovalbumin solution |
Alkaline copper citrate & Folin 72% 15 min Ovalbumin solution |
Key
PBS - Phosphate buffer saline
TES - Hemisodium salt, N-tris-[Hydroxymethyl]-methyl-2-aminoethane sulfonic acid
TCA - Trichloroacetic acid
PTA - Phosphotungstic acid
DOC - Sodium Deoxycholate
NaOH - Sodium Hydroxide
BSA - Bovine serum albumin
