Human Serum Lipoamidase

Hayakawa, Kou; Oizumi, Jun

doi:10.1159/000469138

Cited by 24 publications

(23 citation statements)

References 6 publications

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“…A similar enzyme was described in baker's yeast [5], and later in rabbit and rat tissues [6,7]. The enzyme was identified in human serum [8][9][10] and breast milk [11], by the use of lipoyl-p-aminobenzoic acid (lipoyl-PABA) as an artificial substrate, and the enzyme from breast milk was shown to have a serine residue in the active site [11]. Lipoamidase activity was also found in guinea-pig liver [12] and brain [13], by using lipoyl-PABA as substrate, and was shown to be an integral membrane glycoprotein mainly confined to the microsomal fraction [12].…”

Section: Introductionmentioning

confidence: 89%

Co-purification of human serum lipoamidase and biotinidase: evidence that the two enzyme activities are due to the same enzyme protein

Nilsson¹,

Kågedal²

1993

Biochemical Journal

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A more than 20000-fold purification of human serum lipoamidase is described. This was accomplished by (NH4)2SO4 precipitation and chromatography on DEAE-Sepharose, Blue Sepharose CL-6B and phenyl-Sepharose CL-4B, followed by preparative isoelectric focusing (IEF) and finally by gel-permeation chromatography. Co-precipitation and co-chromatography of lipoamidase and biotinidase activities with equal yields and purification were obtained in all the purification steps, indicating that lipoamidase and biotinidase activities in human serum are due to the same enzyme protein. After preparative IEF, two fractions with both lipoamidase activity and biotinidase activity were found at pI 4.0 and pI 4.4 respectively. The molecular mass of the enzyme was found to be 76 kDa. When 2-mercaptoethanol was used instead of cysteine as stabilizer during the purification procedure, only one major form (pI 4.0) of the enzyme was obtained after preparative IEF. By addition of cysteine, this form was transformed to an enzyme with pI 4.4, indicating that this latter form is a cysteine adduct, produced during the IEF procedure.

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Section: Introductionmentioning

confidence: 89%

Co-purification of human serum lipoamidase and biotinidase: evidence that the two enzyme activities are due to the same enzyme protein

Nilsson¹,

Kågedal²

1993

Biochemical Journal

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“…First, they provide a good fit to the observed extinction wavelength dependence with as few as two populations of grains. Second, formation and destruction processes such as shattering and coagulation that modify grain sizes along many sight lines may naturally produce a power-law size distribution (Biermann & Harwit 1980;Hayakawa & Hayakawa 1988;O'Donnell & Mathis 1997). This type of study began with Oort & van de Hulst (1946), who fitted extinction at visible wavelengths assuming ice grains and a size distribution resembling a PED.…”

Section: History Of Grain Size Distributionsmentioning

confidence: 99%

Dust Grain Size Distributions from MRN to MEM

Clayton

Wolff

Sofia

et al. 2003

ApJ

116

132

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Employing the maximum entropy method (MEM) algorithm, we fit interstellar extinction measurements that span the wavelength range 0.125-3 lm. We present a uniform set of MEM model fits, all using the same grain materials, optical constants, and abundance constraints. In addition, we are taking advantage of improved UV and IR data and better estimates of the gas-to-dust ratio. The model fits cover the entire range of extinction properties that have been seen in the Galaxy and the Magellanic Clouds. The grain models employed for this presentation are the simplistic homogeneous sphere models (i.e., those of Mathis, Rumpl, & Nordsieck in 1977) with two (graphite, silicate) or three (graphite, silicate, amorphous carbon) components. Although such usage is only a first step, the results do provide interesting insight into the use of grain size as a diagnostic of dust environment. We find that the SMC bar extinction curve cannot be fitted using carbon grains alone. This is a challenge to the recent observational result indicating little silicon depletion in the SMC.

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“…A comparison of the properties of cholesterol esterase and lipoamidase has revealed many similarities between the two proteins. For example, both cholesterol esterase and lipoamidase have been demonstrated to be present in serum, liver and human breast milk [4,[15][16][17][18][19][20]. Both enzymes in the liver have apparent by determining enzyme activity in a mutagenized cholesterol esterase with a His435-Gln435 substitution.…”

Section: Introductionmentioning

confidence: 99%

Lipoamidase activity in normal and mutagenized pancreatic cholesterol esterase (bile salt-stimulated lipase)

Hui

Hayakawa

Oizumi

1993

Biochemical Journal

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Purified human milk lipoamidase was digested with endoproteinase Lys-C and the digested peptides were subjected to gasphase microsequence analysis. The sequencing of three isolated peptides of human milk lipoamidase revealed the identity of this protein with human milk bile salt-stimulated lipase (pancreatic cholesterol esterase). The identity of the cholesterol esterase with lipoamidase was confirmed by expressing a recombinant form of rat pancreatic cholesterol esterase and testing for lipoamidase activity of the recombinant protein. The results showed that the recombinant cholesterol esterase displayed both lipolytic and lipoamidase activities and was capable of hydrolysing triacetin and lipoyl-4-aminobenzoate (LPAB). The mechanisms of the esterase and amidase activities of the enzyme were further tested by determining enzyme activity in a mutagenized cholesterol esterase with a His435-->Gln435 substitution. This mutation has been shown previously to abolish enzyme activity against esterase substrates [DiPersio, Fontaine and Hui (1991) J. Biol. Chem. 266, 4033-4036]. We showed that the mutagenized protein was effective in hydrolysing the amidase substrate LPAB and displayed similar enzyme kinetics to those of the native enzyme. These data indicate that the mechanism for the cholesterol esterase hydrolysis of lipoamides is different from that of the hydrolysis of substrates with an ester linkage. The presence of an enzyme in the gastrointestinal tract capable of both ester and amide hydrolysis suggests an important role for this protein in the digestion and absorption processes.

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Human Serum Lipoamidase

Cited by 24 publications

References 6 publications

Co-purification of human serum lipoamidase and biotinidase: evidence that the two enzyme activities are due to the same enzyme protein

Co-purification of human serum lipoamidase and biotinidase: evidence that the two enzyme activities are due to the same enzyme protein

Dust Grain Size Distributions from MRN to MEM

Lipoamidase activity in normal and mutagenized pancreatic cholesterol esterase (bile salt-stimulated lipase)

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