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Current Articles

Enzyme Unit Activity Comparison Chart

Enzyme units vary and the differences can make comparing products from different sources difficult. Unit definitions may appear to be identical however one cannot assume that the potency of a unit is the same between suppliers. Using a common assay procedure, Life Sciences Advanced Technologies has tested AMV RT in our laboratories from the below suppliers. As you can see, there is much deviation between claimed u/µL and actual assay value u/µL. Life Sciences Advanced Technologies by far maintains the closest ratio between claimed units and assay value.
Supplier Claimed U/μL Assayed Value U/μL Deviation Suppliers Unit Definition
LSAT 14.6 14.1 3% 1 Unit = amount required to   incorporate 1 nmol of TTP into acid-insoluble material in 10 min. at 37ºC
Gene Choice 10 5.7 43% 1 Unit = amount required to   incorporate 1 nmol dTTP into acid precipitable material in 10 min. at 37ºC
Invitrogen (cloned) 15 13 12% 1 Unit = amount required to incorporate 1 nmol dTTP into acid-precipitable material in 10 min. at 37ºC, using polyA:oligo (dT)25 as a primer
New England Biolabs 25 4.1 83% 1 Unit = amount required to  incorporate 1 nmol dTMP into acid-insoluble form in 10 min. at 37ºC using Poly A:  oligo (dT) as template primer
Promega 24 4.6 81% 1 Unit = amount required to incorporate 1 nmol deoxynucleotide into acid-precipitable material in 10 min. at 37ºC
Seikagaku 26 9.7 62% 1 Unit = amount required to  incorporate 1 nmol dTMP into acid-insoluble material in 10 min. at 37ºC
USB (Affymetrix) 15 3 80% 1 Unit = amount required to incorporate 1 nmol TMP into acid-insoluble material in 10 min. at 37ºC

Claimed U/µL: the Unit concentration from the supplier’s product labeling.
Assay Value U/µL: the average of 2 assays (4 for LSAT).
Deviation: expressed as the percentage deviation from the value claimed by the supplier against the LSAT result.  LSAT Assay conditions: 4.0mM DTT, 50mM Tris-HCI (pH 8.3), 40mM KCI, 6mM MgCI2, 0.4mM r(A)n(dT)12-18, 0.5mM (3H)-TTP, AMV RT’s diluted with 0.O1M phosphate buffer (pH 7.2), 2mM DTT, 10% glycerol, 0.2% Triton x 100.
Conclusion:Life Sciences Advanced Technologies maintains the closest ratio between claimed units and assay value.If you use significant amounts of an enzyme, it is worth your time to assay different suppliers’ products to ensure a meaningful comparison and good value.

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Trehalose Review Articles
We use trehalose to stabilize some of our enzymes during a freeze-drying process. We used to  purchase trehalose dihydrate from a well-known St. Louis company. However, quality was not consistent, forcing us to screen lots for the presence RNase which can compromise our products. Sometimes there was not lot available that would meet our criteria.Now, we process our own trehalose, both powder and sterile solution for internal use and for sale.

Stabilization, Freeze-Drying, etc.
Enzyme and antibody stabilization is our main interest. Other applications for cells and tissues are beyond our experience, but for those who are interested here is a short list of review articles.
  1. Chen T et al.: (2000) Literature review: supplemented phase diagram of the trehalose-water binary mixture. Cryobiology  v40 pp277-282.
  2. Chen, Y and Z G Lu (2006) Research progress on trehalose used in lyophilization of blood cells – review.   Zhongguo Shi Yan Xue Ye Xue Za Zhi v.14 pp 416-418.
  3. Crowe, J H et al (2003) Stabilization of membranes in human platelets freeze-dried with trehalose., Chemistry and Physics of Lipids. V.122, no.1-2 pp 41-52.
  4. Elbein, A D et al. (2003) Trehalose: a review of properties, history of use and human tolerance, and results of multiple safety studies.  Glycobiology v. 13 no. 4 pp. 17R-27R
  5. Elbein, A D et al. (2003) Review: New insights on trehalose: a multifunctional molecule. Glycobiology, v13 (4j) 17R-27R
  6. 7.    Franzetti , A et al. (2010) Production and Applications of Trehalose Lipid Biosurfactants. European Journal of Lipid Science and Technology. v.9999 no. 999A
  7. Iturriaga, G et al. (2009) Trehalose Metabolism: From Osmoprotection to Signaling. International Journal of Moeculr Sciences v.10 no.9, pp 3793-3810;
  8. Jain N K and I Roy (2009) Effect of trehalose on protein structure. Protein Science v.18 pp 24-36
  9. Richards, A B et al. (2002) Trehalose: a review of properties, history of use and human tolerance, and results of multiple safety studies. Food and Chemical Toxicology  v.40 no.7 pp.871-98.
  10. Ryll, R et al. (2001) Immunological properties of trehalose dimycolate (cord factor) and other mycolic acid-containing glycolipids–a review. Microbiology and Immunology v.45
  11. Schwegman, J J et al. (2005) Practical Formulation and Process Development of Freeze-Dried Products. Pharmaceutical Development and Technology v10 (2)151 – 173 A1
  12. Teramoto , N et al. (2008) Trehalose and Trehalose-based Polymers for Environmentally Benign, Biocompatible and Bioactive Materials. Molecules v.13, no.8, 1773-1816
  13. Ragoonanan, V and A Aksan (2007) Protein Stabilization. Transfusion Medicine and Hemotherapy v.34 pp 246–252

Molecular Biology Grade Trehalose
Our trehalose dihydrate tests negative for RNase/DNase and endotoxin, plus it is very low in other contaminants. Trehalose Solution is a 1M solution made from our Molecular Biology Grade and sterile filtered in a validated process. Full specifications and pricing may be found by following the links above.