Protein Laboratories Rehovot Ltd.
October 2018

Certificate of Analysis & Data Sheet

We are the ONLY company producing leptin antagonists and leptins of farm animals including several fish species.

Pegylated human, mouse, rat and ovine leptins and corresponding leptin antagonists are now available!!!

PLR provides a novel service of pegylation of either existing, or provided or custom-made proteins. All PLR's proteins are carrier free (cf) and can be sold in any requested amount !!!
Human leptin antagonist (mutant L39A/D40A/F41A/I42A) - Cat no. LAN-2
Description: Recombinant human leptin is one polypeptide chain containing 146 amino and additional Ala at N-terminus acids and having a molecular mass of ~ 16 kDa. Human leptin was mutated, resulting in L39A/D40A/F41A/I42A mutant which is leptin antagonist. It was purified by proprietary chromatographic techniques. Preparation of leptin antagonists was published (Niv-Spector et al, Biochem. J 291;221-230 (2005).  
Source: Escherichia coli. 
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Physical Appearance: White lyophilized (freeze-dried) powder. 
Formulation: The recombinant protein was lyophilized from a concentrated (1mg/ml) solution with 0.0045mM NaHCO3. 
Solubility: It is recommended to reconstitute the lyophilized recombinant human leptin antagonist in sterile 0.4% NaHCO3 adjusted, not less than 100µg/ml, which can then be further diluted to other aqueous solutions preferably in presence of carrier protein.  
Stability: Lyophilized recombinant human leptin antagonist although stable at room temperature for several weeks, should be stored desiccated below -18C. Upon reconstitution of recombinant human leptin antagonist mg/ml at 0.1 and up to 2 mg/ml and filter sterilization recombinant human leptin antagonist can be stored at +4C or even room temperature for several weeks making it suitable for long term infusion studies using osmotic pumps. At lower concentration addition of recombinant human leptin antagonistsa carrier protein (0.1% HSA or BSA) is suggested. Please prevent freeze-thaw cycles. 
Purity: Purity of recombinant human leptin antagonist is greater than 98.0% as determined by:
(a) Gel filtration analysis.
(b) Analysis by reducing and non-reducing SDS-PAGE gel. 
Amino Acid Sequence: The sequence of the first five N-terminal amino acids of recombinant human leptin antagonist was determined and was found to be Ala-Val-Pro-Ile-Gln 
Dimers and Aggregates: The purified recombinant human leptin antagonist (16K) consists of > 98% monomers as determined by gel-filtration chromatography. 
Biological Activity: PLR’s recombinant human leptin antagonist is capable of inhibiting leptin-induced proliferation of BAF/3 cells stably transfected with the long form of human leptin receptor. It also inhibits various leptin effects in several in vitro bioassays. 
Endotoxin: Less than 0.1 ng/µg (IEU/µg) of recombinant human leptin antagonist. 
Protein content: Protein quantitation of recombinant human leptin antagonist was carried out by UV spectroscopy at 280 nm using the absorbency value of 0.89 as the extinction coefficient for a 0.1% (1mg/ml) solution at pH 8.0. This value is calculated by the PC GENE computer analysis program of protein sequences (IntelliGenetics).  
Usage: PLR's recombinant human leptin antagonist is furnished for LABORATORY RESEARCH USE ONLY. The product may not be used as drugs, agricultural or pesticidal products, food additives or household chemicals. It is for Research Purposes Only – Commercial Use has been Licensed Exclusively to a Third Party. 
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