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N-acetyl-L-histidine, a Prominent Biomolecule in Brain and Eye of Poikilothermic Vertebrates.

Baslow MH, Guilfoyle DN - Biomolecules (2015)

Bottom Line: In this process, each NAH molecule released to ocular fluid down its gradient carries with it 33 molecules of bound water, effectively transporting the water against a water gradient.In ocular fluid the bound water is released for removal from the eye by the action of NAH acylase.Using MRS, we also document a phylogenetic transition in brain metabolism between poikilothermic and homeothermic vertebrates.

View Article: PubMed Central - PubMed

Affiliation: Nathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Road, Orangeburg, NY 10962, USA. baslow@nki.rfmh.org.

ABSTRACT
N-acetyl-L-histidine (NAH) is a prominent biomolecule in brain, retina and lens of poikilothermic vertebrates. In fish lens, NAH exhibits an unusual compartmentalized metabolism. It is synthesized from L-histidine (His) and acetyl Co-enzyme A. However, NAH cannot be catabolized by lens cells. For its hydrolysis, NAH is exported to ocular fluid where a specific acylase cleaves His which is then actively taken up by lens and re-synthesized into NAH. This energy-dependent cycling suggested a pump mechanism operating at the lens/ocular fluid interface. Additional studies led to the hypothesis that NAH functioned as a molecular water pump (MWP) to maintain a highly dehydrated lens and avoid cataract formation. In this process, each NAH molecule released to ocular fluid down its gradient carries with it 33 molecules of bound water, effectively transporting the water against a water gradient. In ocular fluid the bound water is released for removal from the eye by the action of NAH acylase. In this paper, we demonstrate for the first time the identification of NAH in fish brain using proton magnetic resonance spectroscopy (MRS) and describe recent evidence supporting the NAH MWP hypothesis. Using MRS, we also document a phylogenetic transition in brain metabolism between poikilothermic and homeothermic vertebrates.

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MR spectrum from giant danio brain showing a NAH peak at 1.900 ppm.
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biomolecules-05-00635-f002: MR spectrum from giant danio brain showing a NAH peak at 1.900 ppm.

Mentions: In this study a NAH MR spectral peak was clearly identifiable in fish brain, but not in mammalian brain. Conversely, a NAA MR spectral peak was clearly identifiablein mammalian brain, but not in fish brain. In Figure 2 we show the MR spectrum obtained from giant danio brain, and in Figure 3 from Atlantic salmon brain. In Figure 4 we show the MR spectrum obtained from rat brain, and in Figure 5 the MR spectrum from mouse brain.


N-acetyl-L-histidine, a Prominent Biomolecule in Brain and Eye of Poikilothermic Vertebrates.

Baslow MH, Guilfoyle DN - Biomolecules (2015)

MR spectrum from giant danio brain showing a NAH peak at 1.900 ppm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4496688&req=5

biomolecules-05-00635-f002: MR spectrum from giant danio brain showing a NAH peak at 1.900 ppm.
Mentions: In this study a NAH MR spectral peak was clearly identifiable in fish brain, but not in mammalian brain. Conversely, a NAA MR spectral peak was clearly identifiablein mammalian brain, but not in fish brain. In Figure 2 we show the MR spectrum obtained from giant danio brain, and in Figure 3 from Atlantic salmon brain. In Figure 4 we show the MR spectrum obtained from rat brain, and in Figure 5 the MR spectrum from mouse brain.

Bottom Line: In this process, each NAH molecule released to ocular fluid down its gradient carries with it 33 molecules of bound water, effectively transporting the water against a water gradient.In ocular fluid the bound water is released for removal from the eye by the action of NAH acylase.Using MRS, we also document a phylogenetic transition in brain metabolism between poikilothermic and homeothermic vertebrates.

View Article: PubMed Central - PubMed

Affiliation: Nathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Road, Orangeburg, NY 10962, USA. baslow@nki.rfmh.org.

ABSTRACT
N-acetyl-L-histidine (NAH) is a prominent biomolecule in brain, retina and lens of poikilothermic vertebrates. In fish lens, NAH exhibits an unusual compartmentalized metabolism. It is synthesized from L-histidine (His) and acetyl Co-enzyme A. However, NAH cannot be catabolized by lens cells. For its hydrolysis, NAH is exported to ocular fluid where a specific acylase cleaves His which is then actively taken up by lens and re-synthesized into NAH. This energy-dependent cycling suggested a pump mechanism operating at the lens/ocular fluid interface. Additional studies led to the hypothesis that NAH functioned as a molecular water pump (MWP) to maintain a highly dehydrated lens and avoid cataract formation. In this process, each NAH molecule released to ocular fluid down its gradient carries with it 33 molecules of bound water, effectively transporting the water against a water gradient. In ocular fluid the bound water is released for removal from the eye by the action of NAH acylase. In this paper, we demonstrate for the first time the identification of NAH in fish brain using proton magnetic resonance spectroscopy (MRS) and describe recent evidence supporting the NAH MWP hypothesis. Using MRS, we also document a phylogenetic transition in brain metabolism between poikilothermic and homeothermic vertebrates.

Show MeSH
Related in: MedlinePlus