Reasons for choosing our testing services
ZHONGXI Testing has obtained inspection qualification certifications from multiple countries and regions worldwide. We possess a senior testing team and advanced testing methods, providing independent, impartial, and professional third-party verification services for global carbon projects.
Internationally recognized authority
Certified by multiple international standards such as CNAS, VCS, and GS, with reports universally applicable worldwide.
Global service capability
Covering 140+ countries and regions, it supports on-site detection and remote verification in multiple languages.
Professional experimental methods
Adopt standard experimental methods to ensure accurate and reliable data.
High‑Sensitivity Phosphoglycerate Kinase (PGK) Activity & Quantification Service – From Enzyme Kinetics to Functional Validation
You are searching for phosphoglycerate kinase detection because you need to perform this assay—whether to measure PGK activity in cell lysates for metabolic flux studies, validate recombinant PGK purity and specific activity, screen for PGK inhibitors or activators in drug discovery, or diagnose PGK deficiency (e.g., haemolytic anaemia or neurological disorders). We provide a complete detection service that delivers absolute enzymatic activity (U/mg), kinetic parameters (Km, kcat), protein concentration, and isoform‑specific quantitation using orthogonal spectrophotometric, fluorometric, and mass spectrometry‑based platforms.
What We Detect – From Coupled Enzyme Activity to Direct Product Measurement & Protein Abundance
Our phosphoglycerate kinase detection goes far from simple endpoint ATP or NADH assays. Using continuous spectrophotometric monitoring (340 nm) of NADH oxidation in the coupled reaction with glyceraldehyde‑3‑phosphate dehydrogenase (GAPDH), we measure PGK activity in the forward direction (1,3‑BPG + ADP → 3‑PG + ATP) and reverse direction (3‑PG + ATP → 1,3‑BPG + ADP) with sensitivity down to 0.01 mU/mL and linear range up to 500 mU/mL. For higher sensitivity or when coupled enzymes interfere, we deploy fluorogenic ATP detection (luciferase‑based, real‑time, LOD 0.05 mU/mL) and LC‑MS/MS direct quantitation of ADP/ATP or 3‑PG/1,3‑BPG – eliminating any coupling enzyme artefacts. We also quantify PGK protein concentration via ELISA (sandwich or competitive) with LLOQ of 0.5 ng/mL and targeted PRM‑MS (parallel reaction monitoring) for absolute copy number per cell. For isoform discrimination, we distinguish PGK1 (ubiquitous, testis‑specific in some species) from PGK2 (meiosis‑specific) using isoform‑selective antibodies or isoform‑unique peptide MRM assays.
How Deep We Go – Full Kinetic Characterisation, Inhibition Profiling & Conformational Analysis
We don't just report activity units. Our advanced pipeline includes substrate kinetics for ATP, ADP, 1,3‑BPG, and 3‑PG – determining Km (apparent), Vmax, kcat, and catalytic efficiency (kcat/Km) with 95% confidence intervals (non‑linear regression). For inhibitor screening, we measure IC50 and inhibition mechanism (competitive vs. non‑competitive vs. uncompetitive) against panels of small molecules or peptide inhibitors, using Dixon plots and global fitting of progress curves. We also perform pH activity profiles (pH 5‑9, 0.5 increments), temperature activity profiles (20‑60°C), and thermal inactivation kinetics (t1/2, T50) to assess enzyme stability. For conformational insight, we combine intrinsic tryptophan fluorescence quenching (binding titrations) to determine substrate binding constants (Kd) independent of catalytic turnover, and circular dichroism (CD) spectroscopy to monitor secondary structure changes upon ligand binding. Our microscale thermophoresis (MST) measures Kd down to pM range using only 10 μL of sample per concentration point.
Why Our PGK Detection Stands Out – Substrate Versatility, Low Sample Requirement & Disease Relevance
1. Multiple orthogonal detection methods: We offer four independent activity readouts (NADH coupled, luciferase, LC‑MS, and fluorogenic ADP sensor) – cross‑validation eliminates false positives from interfering enzymes in crude lysates.
2. Ultra‑low sample consumption: With our 384‑well microplate format (5 μL assay volume), we measure activity from as few as 1,000 cultured cells, 1 μL of mouse blood, or 5 μg of tissue lysate. For recombinant PGK, 100 ng pure enzyme is sufficient for full kinetic characterisation.
3. Matrix‑optimised for clinical & research samples: We have validated protocols for red blood cell lysates (PGK deficiency diagnosis), muscle tissue, brain homogenates, liver, cancer cell lines, serum/plasma, and yeast or bacterial extracts. Our lysis buffers preserve activity even after freeze‑thaw.
4. PGK1 vs. PGK2 differentiation: Using isoform‑specific PRM peptides (e.g., PGK1: VVDALGQK; PGK2: DILDLSK), we report absolute fmol/mg protein for each isoform in tissues where both are expressed (e.g., testis, sperm).
5. Regulatory & clinical alignment: Our PGK activity method follows ICSH (International Council for Standardization in Haematology) guidelines for red cell enzyme assays. We have supported three diagnostic studies for PGK deficiency and two IND‑enabling PK/PD studies for PGK‑modulating therapeutics.
Who Relies on Our PGK Detection – Real‑World Impact
A pharmaceutical company studying glycolytic inhibitors for cancer metabolism used our full kinetic profiling (Km for ATP, ADP, and substrate inhibition) to characterise a potent PGK1 inhibitor (IC50 23 nM, mixed mechanism) – data that drove lead optimisation. A clinical diagnostics lab sent us whole blood from a patient with recurrent haemolytic anaemia; we measured PGK activity of 2.1 U/g Hb (normal: 7‑12) and confirmed PGK1 deficiency via MS‑based isoform quantitation. A biotechnology company developing PGK as a biomarker for glioblastoma used our ELISA and activity assays on 200 patient plasma samples – we identified a 3‑fold increase in PGK1 activity that correlated with poor prognosis (p=0.003). An enzyme engineering group sent us 20 PGK mutants from directed evolution; our high‑throughput activity screen (384‑well, 10 μL/well) identified a double mutant with 8‑fold higher kcat at 50°C for industrial biocatalysis.
Ready to Run Your Phosphoglycerate Kinase Detection?
Send us purified PGK (≥1 μg, or ≥100 ng for miniaturised kinetics), cell lysates (≥50 μL, ~10⁶ cells), tissue homogenates (≥100 mg), or whole blood (≥200 μL in anticoagulant). We will perform activity measurement (coupled or direct MS), kinetic characterisation (Km, kcat), inhibitor IC50 (if requested), isoform quantitation (PRM‑MS or ELISA), and a comprehensive report – typically within 3‑7 business days. Request a free consultation; we will design the optimal assay panel (single activity, full kinetics, isoform resolution, or inhibitor screening) for your research, diagnostic, or QC need.