Recombinant Human SI

• Cat.No.: SI-29814TH
• Product Overview: Recombinant fragment of Human SI with N terminal proprietary tag, predicted mwt: 36.52 kDa.

Specification

• Species: Human
• Source: Wheat Germ
• Tag: Non
• Protein Length: 99 amino acids
• Description: This gene encodes a sucrase-isomaltase enzyme that is expressed in the intestinal brush border. The encoded protein is synthesized as a precursor protein that is cleaved by pancreatic proteases into two enzymatic subunits sucrase and isomaltase. These two subunits heterodimerize to form the sucrose-isomaltase complex. This complex is essential for the digestion of dietary carbohydrates including starch, sucrose and isomaltose. Mutations in this gene are the cause of congenital sucrase-isomaltase deficiency.
• Molecular Weight: 36.520kDa inclusive of tags
• Tissue specificity: Expressed in the poorly differentiated crypt cells of the small intestine as well as in the mature villous cells. Expressed at very low levels in the colon.
• Form: Liquid
• Purity: Proprietary Purification
• Storage buffer: pH: 8.00Constituents:0.3% Glutathione, 0.79% Tris HCl
• Storage: Shipped on dry ice. Upon delivery aliquot and store at -80oC. Avoid freeze / thaw cycles.
• Sequences of amino acids: DGESIDTYERDLYLSVQFNLNQTTLTSTILKRGYINKSETRLGSLHVWGKGTTPVNAVTLTYNGNKNSLPFNEDTTNMILRIDLTTHNVTLEEPIEINW
• Sequence Similarities: Belongs to the glycosyl hydrolase 31 family.Contains 2 P-type (trefoil) domains.

Gene Information

• Gene Name: SI sucrase-isomaltase (alpha-glucosidase) [ Homo sapiens ]
• Official Symbol: SI
• Synonyms: SI; sucrase-isomaltase (alpha-glucosidase); sucrase isomaltase; sucrase-isomaltase, intestinal; Oligosaccharide alpha 1; 6 glucosidase
• Gene ID: 6476
• mRNA Refseq: NM_001041
• Protein Refseq: NP_001032
• MIM: 609845
• Uniprot ID: P14410
• Chromosome Location: 3q25.2-q26.2
• Pathway: Carbohydrate digestion and absorption, organism-specific biosystem; Carbohydrate digestion and absorption, conserved biosystem; Digestion of dietary carbohydrate, organism-specific biosystem; Galactose metabolism, organism-specific biosystem; Galactose metabolism, conserved biosystem
• Function: alpha-glucosidase activity; carbohydrate binding; oligo-1,6-glucosidase activity; sucrose alpha-glucosidase activity

Q&As

There is a weak signal in lane 1 at a somewhat higher MW of ~130 kD for SI-0515H. I presume this is the actual enzyme which appears as a ~130 kD protein. This was also observed in the COA for SI-1516H, as shown below, but with a much higher signal. The concentrations of SI-0515H and SI-0516H are 0.12 mg/mL and 0.38 mg/mL, respectively. The signal in the Western blots do not scale comparably for the two enzymes. Am I reading these WB correctly, and if so, what may could account for what appears to be >50-fold differences in signal whereas there only a ~3-fold difference in protein concentration?

The strength of the WB band signal is not only related to the protein concentration, but also related to the binding affinity between protein and the antibody. Due to the differences in structure, SI-0515H and SI-0516H could have different binding affinity to the antibody, thus the WB results are different.

Would it be fair to say that the higher MW band of ~130kD in Lane 1 for both enzymes is likely due to glycosylation?

Yes, it is likely that the band shifting was due to glycosylation.

I see that the expression system was changed from baculovirus to HEK293 from the samples provided back in April compared with the two recent samples. The WB from the samples in April are shown below, which shows a primary signal at ~105 kD, along with some minor bands at 70-80 kD. Was the shift the HEK293 due to the fact that only a single band showed up in the WB?

Different expression system has different post-translational modification. The SI proteins expressed from HEK293 were in soluble form, which is more close to its native status.