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B Boxma

Publications and source records attributed to B Boxma.

4 recordsLinked to original sources
PubMed2001

Nonesterified galacturonic acid sequence homology of pectins.

The methyl ester distribution of pectins was studied with a recently developed enzymatic method. Endopolygalacturonase of Kluyveromyces fragilis was used to degrade pectin and the composition of the degradation products was determined with high-performance anion-exchange chromatography at pH 5. Three characteristics indicative for the distribution of nonesterified galacturonic acid residues were obtained: the percentage of nonesterified galacturonic acid residues liberated of the total number of nonesterified galacturonic acid in the undigested polymer, the proportion of nonesterified mono-, di-, and trigalacturonic acid released, and the ratio of the sum of the peak areas of methyl ester containing oligomers divided by the sum of the peak areas of the nonesterified oligomers detected. From these characteristics and the degree of methyl esterification, the mean sequence similarity of the methyl ester distributions was calculated. Computational techniques commonly employed in the determination of the sequence similarity of DNA and proteins were used to discriminate the various types of distributions found and to construct a distance tree. In general, three types of methyl ester distributions could be discerned in pectin: random, high, and blockwise esterified. This report is the first to describe a parametric approach for the comparison of the substituent distribution in polymers. The importance of this novel approach in the study of the methyl ester distribution and the functional properties of pectin is discussed.

Carbohydrate Conformation↗
PubMed2001

Hydrogenosomes: convergent adaptations of mitochondria to anaerobic environments.

Hydrogenosomes are membrane-bound organelles that compartmentalise the final steps of energy metabolism in a number of anaerobic eukaryotes. They produce hydrogen and ATP. Here we will review the data, which are relevant for the questions: how did the hydrogenosomes originate, and what was their ancestor? Notably, there is strong evidence that hydrogenosomes evolved several times as adaptations to anaerobic environments. Most likely, hydrogenosomes and mitochondria share a common ancestor, but an unequivocal proof for this hypothesis is difficult because hydrogenosomes lack an organelle genome - with one remarkable exception (Nyctotherus ovalis). In particular, the diversity of extant hydrogenosomes hampers a straightforward analysis of their origins. Nevertheless, it is conceivable to postulate that the common ancestor of mitochondria and hydrogenosomes was a facultative anaerobic organelle that participated in the early radiation of unicellular eukaryotes. Consequently, it is reasonable to assume that both, hydrogenosomes and mitochondria are evolutionary adaptations to anaerobic or aerobic environments, respectively.

Journal Article↗
PubMed1999

Hydrogenosomes: eukaryotic adaptations to anaerobic environments.

Like mitochondria, hydrogenosomes compartmentalize crucial steps of eukaryotic energy metabolism; however, this compartmentalization differs substantially between mitochondriate aerobes and hydrogenosome-containing anaerobes. Because hydrogenosomes have arisen independently in different lineages of eukaryotic microorganisms, comparative analysis of the various types of hydrogenosomes can provide insights into the functional and evolutionary aspects of compartmentalized energy metabolism in unicellular eukaryotes.

Adaptation, Physiological↗