Alpha-Klotho Molecular Weight, Sequence & CAS Reference
This reference sheet provides essential structural, chemical, and physical parameters for Alpha-Klotho research compounds. Formulated strictly for laboratory research use, this technical guide outlines published amino acid sequences, calculated molecular weights, counterion salt dynamics, and mass spectrometry analytical standards.
Quick answer
This reference sheet provides essential structural, chemical, and physical parameters for Alpha-Klotho research compounds. Formulated strictly for laboratory research use, this technical guide outlines published amino acid sequences, calculated molecular weights, counterion salt dynamics, and mass spectrometry analytical standards.
Key takeaways
- Alpha-Klotho is a high-molecular-weight single-pass transmembrane protein and humoral factor extensively evaluated in preclinical models investigating cellular senescence, mineral homeostasis, and fibroblast growth factor (FGF) coreceptor signaling.
- The canonical full-length human Alpha-Klotho protein (UniProt accession number Q9UEF7) comprises 1,012 amino acid residues.
- The theoretical unmodified molecular weight of human full-length Alpha-Klotho derived from its 1,012 amino acid sequence is approximately 116.2 kDa.
- The general CAS Registry Number assigned to recombinant human Klotho protein variants is 1312749-34-4.
Physicochemical Specifications & Identity of Alpha-Klotho
Alpha-Klotho is a high-molecular-weight single-pass transmembrane protein and humoral factor extensively evaluated in preclinical models investigating cellular senescence, mineral homeostasis, and fibroblast growth factor (FGF) coreceptor signaling. In laboratory settings, researchers examine both full-length membrane-bound forms and truncated soluble circulating domains.
To maintain rigorous empirical standards across in vitro assays, determining the exact alpha-klotho molecular weight sequence parameters is critical. Chemical variations stem from expression host organisms, terminal truncations, and counterion presence during purification. PX1 Research provides analytical documentation to verify lot-specific mass and identity prior to experimental deployment.
Amino Acid Sequence and Structural Domains
The canonical full-length human Alpha-Klotho protein (UniProt accession number Q9UEF7) comprises 1,012 amino acid residues. The full primary structure includes an N-terminal signal peptide (residues 1–33), a large extracellular domain (residues 34–981), a single transmembrane hydrophobic region (residues 982–1002), and a short inner cytoplasmic tail (residues 1003–1012).
The extracellular domain is composed of two internally homologous glycosidase-like subdomains termed KL1 (residues 34–506) and KL2 (residues 517–953). Shedding by membrane proteases such as ADAM10 and ADAM17 cleaves the extracellular portion, releasing soluble Klotho into circulation. For targeted laboratory studies requiring specific fragments or functional analogs, investigators often utilize modified constructs such as Alpha-Klotho LR, where specific sequence parameters are tailored for distinct binding assays.
Molecular Weight, Glycosylation, and Isotopic Mass Variations
The theoretical unmodified molecular weight of human full-length Alpha-Klotho derived from its 1,012 amino acid sequence is approximately 116.2 kDa. However, because full-length and shed soluble proteins undergo extensive N-linked glycosylation at multiple consensus sites within the KL1 and KL2 domains, the observed molecular weight in western blot or mass spectrometry assays typically ranges between 130 kDa and 140 kDa.
Truncated single-domain recombinant constructs or short synthetic peptide fragments exhibit substantially lower molecular weights. For instance, isolated KL1 domain constructs typically demonstrate an unglycosylated molecular mass of ~54–58 kDa, whereas custom laboratory fragments may range from 1.5 kDa up to 60 kDa depending on expression design. When ordering from our comprehensive catalog of all peptides and recombinant proteins, researchers should consult the lot-specific Certificate of Analysis to review raw empirical mass data.
CAS Registry Number and Chemical Standardizations
The general CAS Registry Number assigned to recombinant human Klotho protein variants is 1312749-34-4. However, researchers should note that specific synthetic domain fragments, custom truncated constructs, or proprietary fusion proteins may not carry an individually assigned CAS index number.
In chemical databases, standard nomenclature refers to Alpha-Klotho as Klotho soluble form, alpha-Klotho precursor, or electrotransfer-derived Klotho domain. When compiling regulatory or institutional chemical safety sheets (MSDS/SDS), referencing the primary UniProt entry (Q9UEF7) alongside the lot-specific chemical formula provides complete traceability for institutional compliance.
Counterion Dynamics: TFA vs. Acetate Salt Forms
Synthetic peptide fragments of Alpha-Klotho synthesized via solid-phase methods are typically isolated as trifluoroacetate (TFA) salts. TFA acts as a strong pairing agent during reverse-phase high-performance liquid chromatography (RP-HPLC) purification. However, residual TFA can lower pH in delicate cell culture assays or interfere with specific enzymatic reactions.
Alternatively, peptides can be converted to acetate salt forms to minimize cell culture toxicity in sensitive in vitro models. The counterion choice directly alters the Net Peptide Content (NPC). A lyophilized peptide sample reported at 98% purity by HPLC may contain 10% to 20% bound counterions and residual moisture by weight. Therefore, calculating absolute molar concentrations requires factoring in the NPC provided on the lot-specific documentation.
Reconstitution Parameters and Buffer Compatibility
Reconstitution protocols for Alpha-Klotho variants depend heavily on whether the construct is a hydrophobic membrane fragment, a soluble domain, or a short synthetic sequence. Lyophilized proteins should be reconstituted using sterile, deionized laboratory-grade water or appropriate physiological buffers (such as PBS, pH 7.4).
To maintain tertiary structure and prevent aggregation of recombinant proteins, brief centrifugation followed by gentle solubilization in aqueous buffers containing 0.1% BSA or carrier protein is often recommended for long-term storage aliquots at -80°C. Researchers calculating stock concentration solutions and serial dilutions should utilize our interactive laboratory reconstitution calculator to eliminate concentration errors during micro-molar preparation.
Comparative Analysis: Alpha-Klotho, Beta-Klotho, and SS-31
Alpha-Klotho forms a distinct functional class alongside related coreceptors and longevity-associated research compounds. Comparing their primary physicochemical parameters illustrates key differences in laboratory application:
While Alpha-Klotho functions primarily as an obligate co-receptor for FGF23 to regulate phosphate and vitamin D metabolism in renal and cardiovascular tissue models, Beta-Klotho shares structural homology (~41% identity) but acts selectively as a coreceptor for FGF19 and FGF21 in metabolic assays. In contrast, smaller synthetic peptides such as SS-31 represent low-molecular-weight (~640 Da) cell-permeable tetrapeptides targeted directly at mitochondrial cardiolipin rather than cell-surface receptor complexes. Reviewing these structural differences allows researchers to select the precise target class in our expanded research hub.
Analytical Verification: HPLC, Mass Spectrometry, and COAs
Establishing structural identity and purity for high-purity research compounds requires rigorous dual-stage analytical testing. High-Performance Liquid Chromatography (RP-HPLC) verifies peak homogeneity and quantifies chemical purity, ensuring freedom from baseline degradation products or truncated synthesis failures.
Electrospray Ionization Mass Spectrometry (ESI-MS) or MALDI-TOF is used to confirm that the observed mass-to-charge ratio matches the theoretical molecular weight of the specified sequence. Laboratory directors can directly download verified batch analyses by accessing our dedicated COA lookup system, guaranteeing complete analytical transparency before initiating experiments.
Quality Assurance and Endotoxin Control at PX1 Research
PX1 Research manufactures and distributes compounds strictly for preclinical in vitro and laboratory research. Every production lot undergoes rigorous quality control within ISO 17025 accredited analytical environments and GMP-compliant production facilities based in the USA.
In addition to HPLC and Mass Spectrometry validation, compounds undergo chromogenic LAL assays to ensure endotoxin levels remain below stringent laboratory thresholds (<0.01 EU/μg). Orders ship directly from our state-of-the-art facilities in California and Arizona with same-day dispatch for orders placed Monday through Friday. Laboratories requiring large-scale allocations or specialized bulk quantities are encouraged to establish a dedicated account through our wholesale portal.
Frequently Asked Questions
What is the theoretical molecular weight of full-length Alpha-Klotho?
The unmodified amino acid chain of full-length human Alpha-Klotho (1,012 residues) has a theoretical molecular weight of approximately 116.2 kDa. Post-translational N-glycosylation increases the observed gel mass to 130–140 kDa.
What is the CAS Registry Number for Alpha-Klotho?
The general CAS Registry Number for recombinant human Klotho protein is 1312749-34-4. Specific truncated sequences or short synthetic fragments may not have an individual CAS index assigned.
How does TFA salt content affect net peptide weight?
Trifluoroacetate (TFA) salt acts as a counterion bound to basic amino acid residues. TFA can account for 10% to 20% of the total mass of a lyophilized peptide. Net peptide content must be factored into concentration calculations to ensure accurate molarity.
Where can I obtain the lot-specific Certificate of Analysis (COA)?
Every product supplied by PX1 Research includes a batch-specific COA. Analytical reports containing HPLC chromatograms and mass spectrometry data can be downloaded directly from our online COA portal.
Can Alpha-Klotho be reconstituted in plain bacteriostatic water?
Reconstitution protocols depend on construct size and domain structure. While small peptides solubilize in sterile water, large recombinant proteins typically require sterile PBS (pH 7.4) or carrier-containing buffers to maintain structural stability.
What is the difference between Alpha-Klotho and Beta-Klotho?
Alpha-Klotho forms a functional receptor complex primarily with FGF23 involved in mineral ion regulation, whereas Beta-Klotho interacts with FGF19 and FGF21 to regulate metabolic and bile acid pathways.
Are PX1 Research compounds approved for human consumption?
No. All products offered by PX1 Research are strictly intended for laboratory research and in vitro experimentation. They are never for human, clinical, or veterinary use.
How should lyophilized Alpha-Klotho be stored upon delivery?
Lyophilized powder should be stored at -20°C to -80°C in a desiccated environment. Reconstituted stock solutions should be aliquoted and stored at -80°C to prevent repeated freeze-thaw cycles.
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