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PubMed2006

Physiological roles of the light, oxygen, or voltage domains of phototropin 1 and phototropin 2 in Arabidopsis.

Phototropins (phot1 and phot2) are plant blue-light receptors that mediate phototropism, chloroplast movement, stomatal opening, rapid inhibition of growth of etiolated seedlings, and leaf expansion in Arabidopsis (Arabidopsis thaliana). Their N-terminal region contains two light, oxygen, or voltage (LOV) domains, which bind flavin mononucleotide and form a covalent adduct between a conserved cysteine and the flavin mononucleotide chromophore upon photoexcitation. The C-terminal region contains a serine/threonine kinase domain that catalyzes blue-light-activated autophosphorylation. Here, we have transformed the phot1 phot2 (phot1-5 phot2-1) double mutant with PHOT expression constructs driven by the cauliflower mosaic virus 35S promoter. These constructs encode either wild-type phototropin or phototropin with one or both LOV-domain cysteines mutated to block their photochemistry. We selected multiple lines in each of the eight resulting categories of transformants for further physiological analyses. Specifically, we investigated whether LOV1 and LOV2 serve the same or different functions for phototropism and leaf expansion. Our results show that the LOV2 domain of phot1 plays a major role in phototropism and leaf expansion, as does the LOV2 domain of phot2. No complementation of phototropism or leaf expansion was observed for the LOV1 domain of phot1. However, phot2 LOV1 was unexpectedly found to complement phototropism to a considerable level. Similarly, transformants carrying a PHOT transgene with both LOV domains inactivated developed strong curvatures toward high fluence rate blue light. However, we found that the phot2-1 mutant is leaky and produces a small level of full-length phot2 protein. In vitro experiments indicate that cross phosphorylation can occur between functional phot2 and inactivated phot1 molecules. Such a mechanism may occur in vivo and therefore account for the functional activities observed in the PHOT transgenics with both lov domains inactivated. The implications of this mechanism with respect to phototropin function are discussed.

Arabidopsis↗

PubMed1985

Dimethyl sulfoxide reductase activity by anaerobically grown Escherichia coli HB101.

Escherichia coli grew anaerobically on a minimal medium with glycerol as the carbon and energy source and dimethyl sulfoxide (DMSO) as the terminal electron acceptor. DMSO reductase activity, measured with an artificial electron donor (reduced benzyl viologen), was preferentially associated with the membrane fraction (77 +/- 10% total cellular activity). A Km for DMSO reduction of 170 +/- 60 microM was determined for the membrane-bound activity. Methyl viologen, reduced flavin mononucleotide, and reduced flavin adenine dinucleotide also served as electron donors for DMSO reduction. Methionine sulfoxide, a DMSO analog, could substitute for DMSO in both the growth medium and in the benzyl viologen assay. DMSO reductase activity was present in cells grown anaerobically on DMSO but was repressed by the presence of nitrate or by aerobic growth. Anaerobic growth on DMSO coinduced nitrate, fumarate, and and trimethylamine-N-oxide reductase activities. The requirement of a molybdenum cofactor for DMSO reduction was suggested by the inhibition of growth and a 60% reduction in DMSO reductase activity in the presence of 10 mM sodium tungstate. Furthermore, chlorate-resistant mutants chlA, chlB, chlE, and chlG were unable to grow anaerobically on DMSO. DMSO reduction appears to be under the control of the fnr gene.

Anaerobiosis↗

PubMedDate not supplied

Antihypertensive effect of riboflavin analogs in rats with mineralocorticoid-induced hypertension.

This study investigated whether the riboflavin analogs, 7,8-dimethyl-10-formylmethyl isoalloxazine (FMI) and 7,8-dimethyl-10-(2'-hydroxyethyl) isoalloxazine (HEI), are effective antihypertensive agents in mineralocorticoid-induced or deoxycorticosterone acetate (DOCA)-salt hypertension. These studies are based on our previous observation tht aldosterone enhances the biosynthesis of renal flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) from riboflavin, and that FMI and HEI competitively inhibit conversion of riboflavin to FMN and reabsorption of Na+ in the kidney of adrenalectomized rats. When 1.6 mg of FMI or HEI were administered simultaneously with 3.0 mg of DOCA, the tail systolic blood pressure (SBP) of unanesthetized rats rose only to 136 +/- 5 mm Hg (standard error of the mean, SEM) compared to 163 +/- 5 mm Hg during DOCA therapy alone (p less than 0.0005). This hypotensive effect of FMI or HEI was noted after the fourth week of treatment and persisted through the ninth week. The rats tolerated the medication well and had no signs of riboflavin deficiency. DOCA administration alone resulted in a 24% increase in iliopsoas muscle Na+ concentration (p less than 0.0005), and a 0.8% increase in the water content of the muscle (p less than 0.025), suggesting a positive Na+ balance. Administration of FMI or HEI blunted the ability of DOCA to increase muscle Na+ concentration (p less than 0.025), water content (p less than 0.01). HEI treatment of the Kyoto strain of spontaneously hypertensive rats (SHR) did not lower their mean SBP. Thus it appears that the hypotensive actions of FMI or HEI are closely associated with their ability to modify the effects of mineralocorticoids on NA+ balance.

Animals↗

PubMed1993

[Hemolysis of isolated erythrocytes by UVA-sensitization of flavins].

Riboflavin (RF), flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) caused hemolysis of isolated rabbit erythrocytes by UVA-sensitization. Hemolysis induced by UVA-sensitization with RF and FMN was inhibited by 1.0 mM histidine and EDTA, and was promoted by 0.15 mM histidine and 0.01 mM NaN3. Hemolysis induced by irradiation in anaerobic condition was smaller than those in aerobic condition. Hemolysis was proceeded in the dark for 5 hours after the UVA-irradiation with RF and FAD. Erythrocyte treated by UVA-sensitization with RF easily caused hypotonic hemolysis.

Animals↗

PubMedDate not supplied

[Influence of enzyme inducers and inhibitors of the metabolism of xenobiotics and of the coenzyme forms of vitamins B1 and B2 on the anti-inflammatory effect of voltaren].

In experiments on 245 male rats there was studied the influence of an inductor of xenobiotic metabolism enzymes, phenobarbital, an inhibitor of microsomal monooxygenases, cobalt chloride, and also coenzyme forms of vitamins B1 and B2, thiamine diphosphate and flavin mononucleotide on the anti-inflammatory effect of voltaren evaluated according to inhibition of an increase of the limb edema, a decrease of pain sensitivity, the blood level of fucose and the liver level of malondialdehyde in rats with adjuvant arthritis. Phenobarbital weakens the anti-inflammatory action of voltaren but at the same time cobalt chloride and thiamine diphosphate potentiate the therapeutic effect of voltaren. Flavin mononucleotide fails to modify the effect of voltaren but decreases however its toxicity.

Acetanilides↗

PubMed1990

The Myxococcus xanthus FprA protein causes increased flavin biosynthesis in Escherichia coli.

The fprA gene is immediately adjacent to the csgA gene (formerly known as spoC) of Myxococcus xanthus. Whereas the csgA gene has an essential role in cell interactions during the developmental cycle, the function of the fprA gene is unknown. Gene disruption was used to determine what affect a null mutation in this gene has on the phenotype of the cell. A csgA-fprA deletion and an fprA frameshift mutation were constructed in vitro in a cloned copy of this locus and then inserted into the M. xanthus chromosome to create a merodiploid with the wild-type and mutant alleles in tandem. The merodiploid was then allowed to segregate one of the two alleles along with the vector sequences in an effort to replace the wild-type allele with the mutant allele. All of the segregants had the wild-type allele, suggesting that a functional fprA gene is essential for vegetative growth. The fprA gene was placed under control of the lacZ transcriptional and translational signals and overexpressed in Escherichia coli, and the new host was examined for any phenotypic changes. A 27-kilodalton protein was observed in sodium dodecyl sulfate-polyacrylamide gels of total-cell protein as predicted from the DNA sequence of this gene. Overexpression of FprA caused the accumulation of a yellow pigment with spectral and redox properties similar to that of the flavins. The pigment cochromatographed with flavin mononucleotide by Silica Gel G thin-layer chromatography. Approximately two-thirds of the total cellular flavin was associated with soluble protein. The major soluble flavin-associated protein was purified on DEAE-Bio-Gel A and Phenyl-Sepharose CL-4B and by polyacrylamide gel electrophoresis. The amino acid composition of the purified protein was similar to that predicted from the DNA sequence of the FprA fusion protein. Apparently, overproduction of FprA (for flavin-associated protein A) in E. coli resulted in a large increase in flavin biosynthesis. Together, these results suggest that the fprA gene encodes a protein that is associated with flavin mononucleotide and has an essential function in M. xanthus.

Amino Acids↗

PubMed1995

Prototropic control of intramolecular electron transfer in trimethylamine dehydrogenase.

The pH dependence of static optical/EPR spectra of trimethylamine dehydrogenase reduced to the level of two equivalents (TMADH2eq) has been examined and indicates the existence of three different states for this iron-sulfur flavoprotein. At pH 6, TMADH2eq exists principally in a form possessing flavin mononucleotide hydroquinone, with its iron-sulfur center oxidized. At pH 8, the enzyme principally contains flavin mononucleotide semiquinone and reduced iron-sulfur, but despite the proximity of the two centers to one another, their magnetic moments do not interact. At pH 10, TMADH2eq exhibits the EPR spectrum that is diagnostic of a previously characterized spin-interacting state in which the magnetic moments of the flavin semiquinone and reduced iron-sulfur center are strongly ferromagnetically coupled. The kinetics of the interconversion of these three states have been investigated using a pH jump technique in both H2O and D2O. The observed kinetics are consistent with a reaction mechanism involving sequential protonation/deprotonation and intramolecular electron transfer events. All reactions studied show a normal solvent kinetic isotope effect. Proton inventory analysis indicates that at least one proton is involved in the reaction between pH 6 and 8, which principally controls intramolecular electron transfer, whereas at least two protons are involved between pH 8 and 10, which principally control formation of the spin-interacting state. The results of these and previous studies indicate that for TMADH2eq, between pH 10 and 6, at least three protonation/deprotonation events are associated with intramolecular electron transfer and formation of the spin-interacting state, with estimated pK alpha values of 6.0, 8.0, and approximately 9.5. These pK alpha values are attributed to the flavin hydroquinone, flavin semiquinone, and an undesignated basic group on the protein, respectively.

Bacterial Proteins↗

PubMed1994

Purification and characterization of the oxygen-sensitive acetohydroxy acid synthase from the archaebacterium Methanococcus aeolicus.

Acetohydroxy acid synthase (EC 4.1.3.18) of the archaebacterium Methanococcus aeolicus was purified 1,150-fold to homogeneity. The molecular weight of the purified enzyme was 125,000, and it contained only one type of subunit (M(r) = 58,000). The amino-terminal sequence had 46 to 57% similarity to those of the large subunits of the eubacterial anabolic enzymes and 37 to 43% similarity to those of the yeast and plant enzymes. The methanococcal enzyme had a pH optimum of 7.6. The pI, estimated by chromatofocusing, was 5.6. Activity required Mg2+ or Mn2+ ions, thiamine pyrophosphate, and a flavin. Flavin adenine dinucleotide, flavin mononucleotide, and riboflavin plus 10 mM phosphate all supported activity. However, activity was strongly inhibited by these flavins at 0.3 mM. The Michaelis constants for pyruvate, MgCl2, MnCl2, thiamine pyrophosphate, flavin adenine dinucleotide, and flavin mononucleotide were 6.8 mM, 0.3 mM, 0.16 mM, 1.6 microM, 0.4 microM, and 1.3 microM, respectively. In cell extracts, the enzyme was sensitive to O2 (half-life = 2.7 min with 5% O2 in the headspace), but the purified enzyme was less sensitive to O2 (half-life = 78.0 min with 20% O2). Reconstitution of the enzyme with flavin adenine dinucleotide increased the sensitivity to O2. Moreover, in the assay the homogeneous enzyme was rapidly inactivated by O2, and the concentration required for 50% inhibition (I50) was obtained with an atmosphere of 0.11% O2. The methanococcal enzyme has similarities to the eubacterial and eucaryotic enzymes, consistent with the ancient origin of the archaebacterial enzyme.

Acetolactate Synthase↗

PubMed1982

Oxidation of naphthalene by a multicomponent enzyme system from Pseudomonas sp. strain NCIB 9816.

The initial reactions in the oxidation of naphthalene by Pseudomonas sp. strain NCIB 9816 involves the enzymatic incorporation of one molecule of oxygen into the aromatic nucleus to form (+)-cis-(1R,2S)-dihydroxy-1,2-dihydronaphthalene. The enzyme catalyzing this reaction, naphthalene dioxygenase, was resolved into three protein components, designated A, B, and C, by DEAE-cellulose chromatography. Incubation of naphthalene with components A, B, and C in the presence of NADH resulted in the formation of (+)-cis-(1R,2S)-dihydroxy-1,2-dihydronaphthalene. The ratio of oxygen and NADH utilization to product formation was 1:1:1. NADPH also served as an electron donor for naphthalene oxygenation. However, its activity was less than 50% of that observed with NADH. Component A showed NAD(P)H-cytochrome c reductase activity which was stimulated by the addition of flavin adenine dinucleotide and flavin mononucleotide. A similar stimulation was observed when these flavin nucleotides were added to the naphthalene dioxygenase assay system. These preliminary observations indicate that naphthalene dioxygenase has properties in common with both monooxygenase and dioxygenase multicomponent enzyme systems.

Alcohol Oxidoreductases↗

PubMed1985

Urinary lumichrome-level catabolites of riboflavin are due to microbial and photochemical events and not rat tissue enzymatic cleavage of the ribityl chain.

The occurrence of 7- and 8-carboxylumichromes as a significant fraction of riboflavin-derived material in rat urine has led to a reexamination of tissues for possible enzymatic activity that could contribute to cleavage at position 10 of the D-ribityl chain of the vitamin. For this, homogenates were incubated in the dark under various conditions with pure [2-14C]riboflavin with and without cofactors prior to extractions with phenol for flavins or chloroform for lumichromes, and high pressure liquid chromatography was used to separate and to quantitate all radioactive compounds. Only unmodified riboflavin and small amounts of flavin mononucleotide (FMN) were found even though the level of detection of known derivatives including 10-(2'-hydroxyethyl)flavin and lumichrome was shown to be extremely sensitive. Hence, rat tissue per se does not appear responsible for significant cleavage of the D-ribityl chain of riboflavin. Rather such cleavage to the lumichrome level must result from the known actions of intestinal microflora and potentially from photolysis.

Animals↗

PubMed2004

Changes in the kinetics and emission spectrum on mutation of the chromophore-binding platform in Vibrio harveyi luciferase.

The recently proposed model for the bacteria luciferase-flavin mononucleotide complex identifies a number of critical intermolecular interactions that define a binding platform for the isoalloxazine ring of flavin [Lin, L. Y., Sulea, T., Szittner, R., Vassilyev, V., Purisima, E. O., and Meighen, E. A. (2001) Protein Sci. 10, 1563-1571]. A key interaction involving van der Waals contact between the isopropyl side chain of alphaVal173 and the 7,8-dimethyl benzene plane of the isoalloxazine chromophore represents an important target to test the validity of the proposed model. Here, structure-function analysis of luciferase variants carrying single point mutations at position alpha173 have verified the functional layout of the active site architecture and implicated this site directly in flavin binding. Moreover, a decrease in the stability of the enzyme-bound C4a-hydroperoxyflavin intermediate in the mutants could account for changes in saturation with the fatty aldehyde substrate. A predicted red-shift on mutation of position alpha173 to increase its polarity confirmed that alphaVal173 was an integral component of the chromophore-binding microenvironment. Introduction of mutations in residues that contact the pyrimidine plane of the isoalloxazine chromophore (alphaA75G/C106V) into the alphaV173A, alphaV173C, alphaV173T, and alphaV173S mutants led to the retention of high levels of enzyme activity (10-40% of wild type) and further red-shifted the emission spectra in the triple mutants. The additivity of the mutation-induced red-shifts in the emission wavelength spectrum provides the basis toward engineering luciferase variants that emit different light colors with the proposed flavin-luciferase model complex as a design reference.

Bacterial Proteins↗

PubMedDate not supplied

Primary processes during the light-signal transduction of phototropin.

Phototropin is a blue-light photoreceptor in plants that mediates phototropism, chloroplast relocation, stomata opening and leaf expansion. Phototropin molecule has two photoreceptive domains named LOV1 (light-oxygen-voltage) and LOV2 in the N-terminus and a serine/threonine kinase domain in the C-terminus, and acts as a blue light-regulated kinase. Each LOV domain binds a flavin mononucleotide as a chromophore and undergoes unique cyclic reactions upon blue-light absorption that comprises a cysteinyl-flavin adduct formation through a triplet-excited state and a successive adduct break to revert to the initial ground state. The molecular reactions underlying the photocycle are reviewed and one of the probable molecular schemes is presented. Adduct formation alters the secondary protein structure of the LOV domains. This structural change could be transferred to the linker between the kinase domain and involved in the photoregulation of the kinase activity. The structural changes as well as the oligomeric structures seem to differ between LOV1 and LOV2, which may explain the proposed roles of each domain in the photoregulation of the kinase activity. The photoregulation mechanism of phototropin kinase is reviewed and discussed in reference to the regulation mechanism of protein kinase A, which it resembles.

Amino Acid Sequence↗

PubMed1986

Kinetic studies of reduction of a 1:1 cytochrome c-flavodoxin complex by free flavin semiquinones and rubredoxin.

The kinetics of reduction by free flavin semiquinones and reduced rubredoxin of the individual components of the 1:1 complex formed between horse heart cytochrome c and Clostridium pasteurianum flavodoxin have been studied. Complex formation did not affect the rate constant for reduction of flavodoxin by 5-deazariboflavin semiquinone, indicating that the accessibility of the flavin mononucleotide (FMN) of complexed flavodoxin is the same as in the free protein. Reduction of the complexed cytochrome c by the neutral flavin semiquinones of lumiflavin and riboflavin was significantly affected by complex formation (2-3-fold rate constant decrease), indicating that there are steric constraints on the accessibility of the cytochrome heme to small exogenous reductants. Reduction of complexed cytochrome c by the negatively charged semiquinones of FMN and Cl2FMN was also characterized. A repulsive electrostatic interaction between the reductants and complexed cytochrome was observed, whereas with free cytochrome an attractive interaction had previously been found. This is consistent with the presence of negative electrostatic potential at the protein interface due to uncompensated flavodoxin carboxylates, as predicted by Matthew et al. [Matthew, J. B., Weber, P. C., Salemme, F. R., & Richards, F. M. (1983) Nature (London) 301, 169-171]. Further, pseudo-first-order rate constants for the reduction of complexed cytochrome by these flavins had a nonlinear concentration dependence, rather than obeying simple second-order kinetics. This is interpreted by using a mechanism involving a rate-determining structural isomerization of the protein complex prior to the second-order electron-transfer step. The magnitude of the decrease in the rate constant for reduction of complexed cytochrome c by the negatively charged reduced rubredoxin was approximately the same as observed for free flavins. Furthermore, simple second-order kinetics were obtained, and the apparent electrostatic interaction between rubredoxin and the complex was attractive. These results suggest that flavodoxin was partially displaced from its complex with cytochrome c by a collisional interaction with rubredoxin. The effects of complexation on the kinetics have been correlated with a solvent-accessible surface representation of the computer-generated model of the flavodoxin-cytochrome c complex [Simondsen, R. P., Weber, P. C., Salemme, F. R., & Tollin, G. (1982) Biochemistry 21, 6366-6375]. The experimental observations are generally consistent with the structural model but clearly require the invocation of dynamic motions at the protein-protein interface.

Clostridium↗

PubMed1974

Kinetics of Activation of Nicotinamide Adenine Dinucleotide Kinase by Phytochrome-Far Red-absorbing Form.

The effects of exogenous redox cofactors and purine analogues on the activation of the NAD kinase by Pfr were examined. Addition of phenazine methosulfate, flavin mononucleotide, or methylene blue increased the activation of NAD kinase by red light in a partially purified preparation of phytochrome. Phenazine methosulfate and flavin mononucleotide do not absorb light in the red or far red region, so they do not act as light receptors in this activation. Thus they probably intervene in electron transfer between phytochrome and NAD kinase. Addition of kinetin with these compounds increased photopotentiation further. In the presence of phenazine methosulfate and kinetin, the activation of NAD kinase by red light was counteracted by illumination with far red light immediately after red light.The relation between the dose of illumination with red light and the degree of activation of NAD kinase was measured. Illumination for 5 minutes with 800 ergs cm(-2) sec(-1) of red light was sufficient to obtain maximal activation. In the dark, the activated state of NAD kinase was maintained for about 10 min and then rapidly lost. The time of preservation of the activated state was greatly shortened by illumination with far red light, indicating the participation of phytochrome.

Journal Article↗

PubMed2005

The 1.3 A crystal structure of the flavoprotein YqjM reveals a novel class of Old Yellow Enzymes.

Here we report the crystal structure of YqjM, a homolog of Old Yellow Enzyme (OYE) that is involved in the oxidative stress response of Bacillus subtilis. In addition to the oxidized and reduced enzyme form, the structures of complexes with p-hydroxybenzaldehyde and p-nitrophenol, respectively, were solved. As for other OYE family members, YqjM folds into a (alpha/beta)8-barrel and has one molecule of flavin mononucleotide bound non-covalently at the COOH termini of the beta-sheet. Most of the interactions that control the electronic properties of the flavin mononucleotide cofactor are conserved within the OYE family. However, in contrast to all members of the OYE family characterized to date, YqjM exhibits several unique structural features. For example, the enzyme exists as a homotetramer that is assembled as a dimer of catalytically dependent dimers. Moreover, the protein displays a shared active site architecture where an arginine finger (Arg336) at the COOH terminus of one monomer extends into the active site of the adjacent monomer and is directly involved in substrate recognition. Another remarkable difference in the binding of the ligand in YqjM is represented by the contribution of the NH2-terminal Tyr28 instead of a COOH-terminal tyrosine in OYE and its homologs. The structural information led to a specific data base search from which a new class of OYE oxidoreductases was identified that exhibits a strict conservation of active site residues, which are critical for this subfamily, most notably Cys26, Tyr28, Lys109, and Arg336. Therefore, YqjM is the first representative of a new bacterial subfamily of OYE homologs.

Amino Acid Sequence↗

PubMed2000

The flavin coenzymes: a new class of group I intron inhibitors.

Effects of the coenzyme flavin mononucleotide (FMN) and its analogs on the self-splicing of primary transcripts of the phage T4 thymidylate synthase gene (td) have been investigated. Among all flavins and analogs tested, the lumichrome was the most inhibitory. The kinetic analysis demonstrated that FMN acts as a competitive inhibitor for the td intron RNA with a Ki of 1.86 mM although it does not possess a guanidino group in its structure. FMN is able to inhibit the first step of the self-splicing, thus identifying FMN as a novel class of group I intron splicing inhibitors. The specificity of the splicing inhibition by FMN is predominantly due to changes in Km but not k(cat). The splicing inhibition is believed to be due to the interference with the affinity of GTP for the intron RNA. The analysis of the inhibitory concentration and structural examination suggests that the key structural features in FMN responsible for the inhibition of splicing may be an alloxazine group.

Bacteriophage T4↗

PubMed1983

Resonance Raman spectra of flavin semiquinones stabilized by N5 methylation.

Resonance Raman spectra are reported for the semiquinone of N5-methyl derivatives of FMN (flavin mononucleotide) in H2O and 2H2O, 8-chloro FMN and FAD (flavin adenine dinucleotide) with 647.1 nm excitation, in the first pi-pi absorption band, using KI to quench fluorescence. The spectral pattern is similar to that of oxidized flavin, in its first absorption band, but with appreciable shifts, up to approx. 50 cm-1, in corresponding frequencies. There are also significant shifts with respect to the previously reported resonance Raman spectrum of flavodoxin semiquinone, reflecting the substitution of CH3 for H at N5. The N5-methyl FAD semiquinone spectrum is also reported for 514.5 nm excitation, in resonance with the second pi-pi transition. The intensity pattern is quite different, the spectrum being dominated by a band at 1611 cm-1, assigned to a mode localized primarily on the central pyrazine ring.

Carrier Proteins↗

PubMedDate not supplied

Foetal macrosomia and erythrocyte acid phosphatase (ACP1) polymorphism in diabetic and normal pregnancy.

Both in diabetic and in normal pregnancy the proportion of macrosomic fetuses is much lower among newborns carrying Pc allele of erythrocyte acid phosphatase (ACP1) than among other ACP1 genotypes. In diabetic pregnancy the well known increased incidence of fetal macrosomia has been observed only among fetuses which do not carry this allele. ACP1 probably functions as a flavin-mononucleotide phosphatase. Since Pc allele is associated with the highest enzymatic activity it is likely that subjects carrying this gene may have a relatively lower concentration of flavin-mononucleotide cofactors and in turn a reduced rate of metabolic activities controlled by flavoenzymes. It is possible that in fetuses carrying Pc, flavo-enzyme activities are regulated at a level that does not allow a full response to stimuli (both genetic and/or environmental) aimed to maximize fetal growth.

Acid Phosphatase↗