We design and supply a wide range of assay kits to help you measure amino acids, their precursors, and related compounds, as well as the enzymes involved in their synthesis and metabolism. We also provide kits for nucleotide synthesis and metabolism analysis.

Most of these kits use enzymatic reactions to generate measurable outputs, detected with either a colorimetric or fluorometric plate reader.

Amino acid assays

Amino acids are the building blocks of proteins. They contain both amino and carboxyl groups and are classified by the chemical nature of their side chains: aromatic, aliphatic, hydrophilic, acidic, or basic.

There are 22 amino acids in proteins, 20 used directly in protein synthesis and two formed through post-translational modifications, such as hydroxyproline (ab222941) found in collagen (ab222942, ab241015).

Beyond protein synthesis, amino acids serve as signaling molecules, neurotransmitters, and energy sources, contributing to glycolysis, gluconeogenesis, or the TCA cycle. While many amino acids can be synthesized from metabolic intermediates, nine are essential and must come from the diet:

• Branched-chain amino acids: leucine, isoleucine, valine (ab234627)
• Aromatic amino acids: tryptophan (ab211098), phenylalanine (ab241000, ab83376)
• Polar amino acids: threonine (ab239726), histidine, lysine
• Sulfur-containing amino acid: methionine (ab234041)

Serine and glycine (ab211100) are conditionally essential, synthesized from 3-phosphoglycerate (ab252891) at an energy cost. The TCA cycle metabolite α-ketoglutarate (ab83431) is a key precursor for non-essential amino acids.

For example:

• Glutamate is formed from α-ketoglutarate and ammonia by glutamate dehydrogenase (ab102527).

• Glutamine is produced from glutamate by glutamine synthetase (ab284572).

• Transamination reactions generate alanine and aspartate:

  • Aspartate aminotransferase (ab105135) uses glutamate and oxaloacetate to form aspartate.
  • Alanine aminotransferase (ab105134) uses glutamate and pyruvate to form alanine.

Nucleotide synthesis and metabolism assays

Nucleotides are the building blocks of DNA and RNA, but they also play critical roles in energy transfer, redox reactions, signaling, and neurotransmission.

Structure and Synthesis

Nucleotides consist of a sugar (ribose or deoxyribose), a purine or pyrimidine base, and one or more phosphate groups. Purines (adenine, guanine, xanthine, hypoxanthine) have a fused-ring structure, while pyrimidines (uracil, thymine, cytosine) have a single ring.

Purine synthesis begins with PRPP and leads to inosine monophosphate (IMP), which can branch into AMP or GMP pathways:

• AMP synthesis starts with adenylosuccinate synthetase and uses GTP.
• GMP synthesis starts with IMP dehydrogenase and uses ATP, forming XMP.

Catabolism involves:

• Adenosine: inosine by adenosine deaminase (ab211093, ab204695)
• Inosine: hypoxanthine by purine nucleotide phosphorylase (ab204706)
• Hypoxanthine: xanthine - uric acid by xanthine oxidase (ab102522)

For guanine nucleotides:

• Guanosine: guanine by purine nucleotide phosphorylase
• Guanine: xanthine by guanine deaminase, ending in uric acid (ab65344)

Metabolic regulation and degradation

Nucleosides and nucleotides play vital roles in cellular processes, including the storage and transfer of genetic information (DNA and RNA), energy metabolism (ATP), and cell signaling (cAMP). They also serve as cofactors in enzymatic reactions and play a key role in processes such as transcription, translation, and signal transduction.

Metabolic regulation and degradation of nucleotides and nucleosides are essential processes that maintain cellular function and energy balance.

These molecules play a key role in various biochemical pathways, and their breakdown is tightly regulated to prevent toxicity and ensure efficient energy use. The catabolism of nucleotides involves complex enzymatic reactions that result in the production of waste products, such as uric acid or metabolites, that can be recycled for further cellular activities.

Detection methods for DNA damage

Several techniques are available for detecting DNA damage, including methods that assess strand breaks, mutations, and other types of genetic lesions.

• The comet assay is a widely used technique for detecting DNA strand breaks and other types of DNA damage. The Comet Assay Kit (3-well slides) ab238544 provides an efficient tool for conducting this assay.

• AP site detection methods are used to identify locations where the DNA backbone is intact, but a purine or pyrimidine base has been lost. The DNA damage assay kit (AP sites, Colorimetric) ab211154 is a valuable tool for accurately detecting AP sites in DNA samples.