DESCRIPTION

Pepsinogen I belongs to the peptidase A1 family. The gene endoces a 388 amino acid protein with a 15 amino acid signal peptide and 46 amino acid propeptide. Pepsinogen I is secreted only by the chief cells of the corpus, and its serum level decreases with increasing grade of the corpus atrophy (loss of oxyntic glands). Low serum levels of pepsinogen I are indicative of chronic atrophy, a risk factor for gastric cancer.

PRINCIPLE OF THE ASSAY

A capture antibody is pre-coated onto the bottom of wells which binds to analyte of interest. A detection antibody also binds to the analyte. Horseradish peroxidase (HRP)-conjugated secondary antibody binds to the detection antibody. TMB acts as the HRP substrate and the solution color will change from colorless to blue. A stop solution containing sulfuric acid turns solution yellow. The color intensity is proportional to the quantity of bound protein which is measurable at 450 nm with the correction wavelength set at 630 nm.

PRECISION

Intra-assay Precision (Precision within an assay) Three samples of known concentration were tested 20 times on one plate to assess intra-assay precision. Inter-assay Precision (Precision between assays) Three samples of known concentration were tested in 24 separate assays to assess inter-assay precision.

Intra-assay Precision

Sample	n	Mean (ng/mL)	SD	CV%
1	20	24.36	1.33	5.5
2	20	6.43	0.33	5.2
3	20	0.65	0.06	8.9

Inter-assay Precision

Sample	n	Mean (ng/mL)	SD	CV%
1	24	23.79	1.86	7.8
2	24	5.78	0.49	8.5
3	24	0.48	0.04	9.0

RECOVERY

The recovery of human PGA5 spiked to three different levels throughout the range of the assay in various matrices was evaluated.

Sample Type		Average% of Expected	Range (%)
Human plasma	1:2	90	76-108
	1:4	95	75-115
Cell culture supernatant	1:2	109	78-127
	1:4	99	83-117

LINEARITY

To assess the linearity of the assay, three samples were spiked with high concentrations of human PGA5 in various matrices and diluted with the appropriate Sample Diluent to produce samples with values within the dynamic range of the assay.

		Human plasma	Cell culture supernatant
1:2	Average% of Expected	84	112
	Range (%)	80-90	109-115
1:4	Average% of Expected	91	114
	Range (%)	78-101	96-124
1:8	Average% of Expected	96	95
	Range (%)	83-104	81-119
1:16	Average% of Expected	95	96
	Range (%)	88-99	75-116

CALIBRATION

This immunoassay is calibrated against a highly purified recombinant human PGA5 produced at Sunlong Medical™.

Ordering & shipping

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