Fish muscle is naturally rich in adenosine triphosphate (ATP), the nucleotide that provides the energy for muscle contraction and swimming. Following capture and respiratory arrest, ATP in fish muscle is rapidly hydrolyzed to inosine 5'-monophosphate (IMP). Because IMP is unstable and can be further degraded to inosine and hypoxanthine by autolytic and bacterial enzymes, its abundance is widely recognized as a biochemical indicator of fish freshness. Consequently, fishmeal prepared from fresh raw material is naturally enriched in dietary IMP.
Among available sources, anchovy fishmeal is especially valued in aquaculture for its high digestibility, protein content, balanced amino acid profile, and essential fatty acids. While anchovy fishmeal naturally contains nucleotides, IMP levels are highly variable (Table 1) and are not consistently reported in standard composition tables.
Principle
PRECICE® Fishmeal IMP Assay Kit provides an enzymatic tool for measuring IMP content samples by long-UV
spectrophotometry.
PRECICE® Fishmeal IMP Assay Kit is based on the use of recombinant IMP-specific dehydrogenase that allows irreversible
and quantitative conversion of IMP to NADH. The NADH formed can be quantified by measuring specific
absorbance at 340nm. For maximal accuracy, the assays are run with and without IMPDH enzyme in parallel. The
absorbance rate observed in the absence of IMPDH is used as blank and is subtracted from the absorbance rate
measured in its presence.
Nucleotides content in fishmeal
Table 1. Nucleotides Content in Fishmeal Samples (Anchovy)
Compound
Fishmeal 1
Fishmeal 2
Fishmeal 3
Fishmeal 4
Guanine (g/kg)
1.23
1.49
1.51
1.26
Hypoxanthine (g/kg)
0.54
1.02
0.81
2.29
Inosine (g/kg)
1.93
1.79
1.90
0.76
IMP (g/kg)
3.20
1.48
2.14
0.23
AMP (g/kg)
0.42
0.34
0.34
0.26
ADP (g/kg)
0.06
0.06
0.06
0.08
ATP (g/kg)
0.05
0.03
0.02
0.02
This variability explains why supplementation studies dominate the literature, even though fresh fishmeal itself can provide IMP derived from ATP breakdown in muscle tissue.
Accurate quantification of IMP in fishmeal is therefore essential for evaluating feed quality and nutritional value. High-performance liquid chromatography (HPLC) remains the reference method, as it enables precise and quantitative measurement of IMP concentrations with high accuracy and precision.
Figure 1: Full spectra of nucleotides, nucleosides and bases present in anchovy fishmeal sample 1 analyzed by ion-paired reverse phase HPLC by NOVOCIB showing high level of IMP (320mg/100g)Figure 2: Full spectra of nucleotides, nucleosides and bases present in anchovy fishmeal sample 1 analyzed by ion-paired reverse phase HPLC by NOVOCIB with low level of IMP (23mg/100g).
As a faster alternative, NOVOCIB has developed novel PRECICE® IMP Assay Kit, a cost-efficient enzymatic approach. In this assay, IMP is enzymatically converted to xanthosine monophosphate (XMP) with concomitant reduction of NAD to NADH. The NADH formed is then quantified spectrophotometrically at 340 nm, with absorbance developing only in the presence of the specific enzyme. This innovation enables rapid and reliable measurement of IMP directly in fishmeal, supporting both quality control and nutritional evaluation in aquaculture feed production.
Kit Content:
Once dissolved, the reagents provided in the kit are not stable and should be used the day of preparation.
A standard PRECICE® Fishmeal IMP Assay Kit contains contains:
one sealed 96-well microplate (roundbottom 96-well plate Corning, Costar®, ref. 3797) prefilled with IMP-dehydrogenase enzyme
and IMP standards (3 lanes);
one tube “Cofactor 1”;
one tube “Cofactor 2”;
one vial "Reaction buffer”;
IMP concentration comparison
Sample
IMP (g/kg) - HPLC
IMP (g/kg) - Enzymatic PRECICE Kit
FISHMEAL 1
1.33
1.26
FISHMEAL 2
1.95
1.90
FISHMEAL 3
2.30
2.13
FISHMEAL 4
0.69
0.58
FISHMEAL 5
2.91
3.00
FISHMEAL 6
2.11
2.11
FISHMEAL 7
0.90
0.84
FISHMEAL 8
1.64
1.56
FISHMEAL 9
2.13
2.36
FISHMEAL 10
3.94
4.16
R² /HPLC data
Recovery (Enzymatic versus HPLC)
0.99
101%
The correlation between HPLC and PRECICE kit measurements is extremely strong: Pearson r ≈ 0.99 and R² ≈ 0.98, showing that both methods yield highly consistent results.
Buy the Kit
#REF
SIZE
PRICE
#0700-06-12
PRECICE® Fishmeal IMP Assay Kit (microplate reader, for 12 samples) including calibration curve with IMP
