| Catalog | Product Name | EC No. | CAS No. | Source | Price |
|---|---|---|---|---|---|
| DIA-271 | Native Calf Adenosine Deaminase | EC 3.5.4.4 | 9026-93-1 | Calf Spleen | Inquiry |
| DIA-272 | Native Cystathionine-β-synthase | EC 4.2.1.22 | 9023-99-8 | Inquiry | |
| DIA-293 | Cystathionine-β-synthase, Recombinant | EC 4.2.1.22 | 9023-99-8 | Inquiry | |
| DIA-682 | Cystathionine B-lyase (CBL) | 9055-05-4 | Inquiry | ||
| EXWM-4568 | adenosine deaminase | EC 3.5.4.4 | 9026-93-1 | Inquiry | |
| NATE-0032 | Adenosine deaminase Bovine, Recombinant | EC 3.5.4.4 | 9026-93-1 | E. coli | Inquiry |
| NATE-1009 | Adenosine deaminase, Recombinant | EC 3.5.4.4 | 9026-93-1 | E. coli | Inquiry |
| NATE-1010 | Recombinant Adenosine deaminase from Pseudomonas aeruginosa | EC 3.5.4.4 | E. coli | Inquiry | |
| NATE-1146 | Cystathionine β-lyase, Recombinant | EC 4.4.1.8 | Inquiry |
Homocysteine is a sulfur-containing amino acid intermediate formed during methionine metabolism. In biological samples, homocysteine may occur as free reduced homocysteine, disulfide forms, mixed disulfides, and protein-bound species. Assays intended to measure total homocysteine must therefore release and reduce the different forms before the resulting free homocysteine can enter the analytical reaction.
Enzymatic homocysteine assays can use direct substrate-selective cleavage, substrate-cycling reactions, or multi-enzyme pathways that convert homocysteine into a measurable product. Depending on the assay design, the signal may be generated from hydrogen sulfide, ammonia, α-ketobutyrate, adenosine-related intermediates, NADH consumption, or a coupled reporter reaction.
Creative Enzymes supplies homocysteinase, cystathionine β-synthase, cystathionine β-lyase, adenosine deaminase, and related enzyme components for homocysteine assay reagent development. Native and recombinant options are available for method comparison, formulation development, and alternative-source evaluation.
Homocysteine assay development involves two connected analytical challenges. The first is converting the different circulating forms of homocysteine into a consistently measurable form. The second is selecting an enzyme pathway that responds specifically and reproducibly to the released homocysteine while controlling background from other sulfur-containing compounds and sample components.
Only a portion of homocysteine in serum or plasma is present as free reduced homocysteine. A total homocysteine method generally requires a pretreatment step that reduces disulfide bonds and releases protein-associated homocysteine before enzymatic detection.
Relevant pretreatment considerations include:
Incomplete reduction can lead to under-recovery, whereas an incompatible reducing system may inhibit the analytical enzymes or alter the final signal reaction.
After pretreatment, free homocysteine can be measured through several enzyme architectures. A direct method may use homocysteinase to cleave homocysteine, while a cycling method may repeatedly convert homocysteine through cystathionine-related reactions to amplify the analytical response.
Representative strategies include:
These approaches use different enzymes, cofactors, reporter systems, and interference-control strategies. Products intended for one reaction architecture should not be assumed to be interchangeable with components from another method.
The selected pretreatment, homocysteine-conversion pathway, and signal-generation system together determine the assay's analytical behavior. Each component should therefore be evaluated within the complete reagent formulation rather than on enzyme activity alone.
Hcyase, also described as homocysteinase, catalyzes the γ-lysis of L-homocysteine and produces α-ketobutyrate, ammonia, and hydrogen sulfide. One or more of these reaction products can be connected to an optical, electrochemical, or coupled enzymatic detection system.
A direct Hcyase-based method may offer:
Method development must confirm selectivity against related sulfur-containing amino acids and establish that the sample-reduction chemistry does not inhibit Hcyase activity.
A substrate-cycling design can combine cystathionine β-synthase and cystathionine β-lyase. In a representative cycle, CBS converts homocysteine into cystathionine in the presence of the required cosubstrate and cofactors. CBL then cleaves cystathionine, regenerating homocysteine while producing α-ketobutyrate and ammonia.
The principal products include:
Regeneration of homocysteine can amplify formation of the measurable reaction product. The degree of amplification depends on the balance between the two enzymes, cosubstrate concentrations, cofactor availability, and reaction timing.
Figure 1. Schematic of homocysteine metabolism and formation of endogenous hydrogen sulfide (Adapted from Sen et al., 2010)
Adenosine deaminase may be used as an auxiliary enzyme in selected homocysteine methods involving S-adenosylhomocysteine or adenosine-related intermediates. ADA converts adenosine to inosine and can help drive or connect the upstream reaction to a downstream detection sequence.
Available ADA sources include:
ADA should be selected according to the complete pathway because source, activity definition, formulation, molecular properties, and compatibility with upstream enzymes can vary among products.
The products currently listed in this category are enzyme raw materials for homocysteine reagent and kit development. A ready-to-use complete homocysteine assay kit is not presently displayed on the public product page.
Development support may include:
Customers seeking a complete kit or a custom configured reagent should contact Creative Enzymes to confirm current availability and project requirements.
| Enzyme or Component | Potential Role | Representative Products | Selection Considerations |
|---|---|---|---|
| Homocysteinase | Direct cleavage of L-homocysteine to α-ketobutyrate, ammonia, and hydrogen sulfide | Hcyase | Homocysteine specificity, thiol interference, reducing-agent tolerance, reaction rate, and signal pathway |
| Cystathionine β-synthase | Converts homocysteine into cystathionine as part of a substrate-cycling reaction | Native CBS; Recombinant CBS | Source, cofactor requirements, cosubstrate response, activity, stability, and compatibility with CBL |
| Cystathionine β-lyase | Cleaves cystathionine, regenerates homocysteine, and produces α-ketobutyrate and ammonia | Cystathionine B-lyase | Cystathionine activity, enzyme ratio, cofactor compatibility, side activities, and cycling efficiency |
| Adenosine deaminase | Auxiliary conversion of adenosine in selected S-adenosylhomocysteine-related pathways | Native Calf ADA; Recombinant Bovine ADA; Recombinant ADA | Species and source, activity definition, purity, buffer, stabilizers, and upstream pathway compatibility |
| Reduction reagent | Releases protein-bound and disulfide-linked homocysteine before enzymatic detection | Assay-specific reducing system | Reduction efficiency, enzyme inhibition, reagent stability, reaction timing, and sample matrix |
| Reporter system | Converts α-ketobutyrate, ammonia, hydrogen sulfide, adenosine-related products, or reducing equivalents into a measurable signal | Assay-specific coupling and reporter components | Signal sensitivity, background, endpoint or kinetic format, platform compatibility, and interference profile |
Determine whether the assay is intended to measure:
Total homocysteine and free homocysteine are not equivalent measurands. The sample-treatment step must match the intended analytical target.
The assay may use:
The chosen architecture determines which enzymes, substrates, cofactors, and reporter components are required.
Multi-enzyme assays require balanced reaction rates. Excessive or insufficient activity at one step may change the measuring range, response time, background, or reagent cost.
Evaluation may include:
Supplier activity units should be interpreted according to the stated assay conditions and should not be compared without reviewing the unit definitions.
Important formulation factors include:
An enzyme that performs well in its standard activity assay may become unstable or inhibited in the complete homocysteine reagent.
Potential interferents and sources of background may include:
The relevant interference profile depends on the pretreatment procedure, enzyme architecture, signal product, sample matrix, and analytical platform.
Need Help Selecting Homocysteine Assay Enzymes?
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Q1. What is total homocysteine?
Q2. Why is a reduction step required?
Q3. Which enzyme can directly detect homocysteine?
Q4. How does a CBS–CBL cycling assay work?
Q5. What is the role of adenosine deaminase in homocysteine testing?
Q6. Can enzymes from different homocysteine methods be combined freely?
Q7. Do you offer native and recombinant enzymes?
Q8. What should be evaluated when selecting a homocysteine assay enzyme?
Q9. Can Creative Enzymes help develop a complete homocysteine reagent?
