Protein Laboratories Rehovot Ltd.
May 2019

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 - Cat no. LEP-5 GENE ID 3952
Description: Recombinant protein - human leptin, one polypeptide chain containing 146 amino and additional Ala at N-terminus acids and having a molecular mass of ~ 16 kDa., Human leptin was purified by proprietary chromatographic techniques, see Raver et al. Gen. Comp. Endocrinol. (2002). 
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 in sterile water or 0.4% NaHCO3 adjusted to pH 8-9, not less than 100µg/ml, which can then be further diluted to other aqueous solutions.  
Stability: Lyophilized recombinant human leptin although stable at room temperature for several weeks, should be stored desiccated below -18C. Upon reconstitution at > 0.1 human leptin mg/ml and up to 2 mg and filter sterilization recombinant human leptin can be stored at +4C or even room temperature for several weeks. At lower concentration addition of a carrier protein (0.1% HSA or BSA) is suggested. Please prevent freeze-thaw cycles. 
Purity: Purity of recombinant human leptin is greater than 95.0% as determined by:
(a) Gel filtration analysis of the recombinant protein.
(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 was determined and was found to be Ala-Val-Pro-Ile-Gln

Dimers and Aggregates: The purified recombinant human leptin (16K) consists of > 93% monomers as determined by gel-filtration chromatography. 
Biological Activity: PLR’s recombinant human leptin is fully biologically active as evidenced by inducing proliferation of BAF/3 cells stably transfected with the long form of human leptin receptor.  
Endotoxin: The endotoxin content of recombinant human leptin is less than 0.1 ng/µg (IEU/µg). 
Protein content: Protein quantitation in recombinant human leptin was carried out by UV spectroscopy at 280 nm using the absorbency value of 0.87 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: Recombinant human leptin is offered by PLR for laboratory research  
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