A Specific Association Between the Glyoxylic‐Acid‐Cycle Enzymes Isocitrate Lyase and Malate Synthase

Abstract

There is accumulating evidence that metabolic pathways are organized in vivo as multienzyme clusters or metabolons. To assess interactions between consecutive enzymes of a pathway in vitro, it is usually essential to modify the physical properties of water around the enzymes, e.g. by immobilizing the latter onto a solid support. Such immobilized enzyme preparations can be embedded in agarose gels and used for affinity electrophoresis [Beeckmans, S., Van Driessche, E. & Kanarek, L. Cell. Biochem. 43, In this study we use the aforementioned technique to investigate the association between two plant glyoxylic acid cycle enzymes, i.e. isocitrate lyase and malate synthase. A specific histochemical staining technique is described for both enzymes. Affinity electrophoresis using either isocitrate lyase or malate synthase as the immobilized enzyme clearly shows that associations are formed between both enzymes. Moreover, experiments with metabolically unrelated enzymes prove that the observed interaction is specific.In recent years it was realized that the aqueous-phase properties in the interior of a cell seem to be essentially different from those of an ordinary aqueous solution (Beeckmans et al

Molecular Characterization of Mutants of the Acetate Regulatory GenefacBofAspergillus nidulans

“…The FacB protein may be involved in the formation of complexes with ACS, ICL, and MAS or may form a structural component of the glyoxysome in which these enzymes are contained. ICL and MAS have been shown to form a specific complex by direct interaction in Zea mays (Beeckmans et al, 1994). It cannot be excluded that the facB12 and facB23 alleles affect some posttranslational modification of these enzymes.…”

Exploration of key genes and pathways in response to submergence stress in red clover (Trifolium pratense L.) by WGCNA

“…The glyoxylate pathway, also known as the glyoxylate cycle, is a process that is only present in plants and microorganisms functioning in lipid-to-sugar conversion. It plays an important role in plant growth and development and resistance to stress conditions and has been relatively well-studied in rice [45] . Among the three catalase isozymes isolated from tobacco (Nicotiana tabacum), CAT1 is mainly responsible for scavenging H 2 O 2 produced by photorespiration, CAT2 scavenges H 2 O 2 produced by oxidative stress, and CAT3 mainly scavenges H 2 O 2 produced by the glyoxylate cycle [46] .…”

Activity staining of isocitrate lyase after electrophoresis on either native or sodium dodecyl sulfate polyacrylamide gels

“…MTT and DCPIP were used in the coupling reactions for detecting the ICL activity after electrophoresis on either native or SDS-PAGE gels. Our method has several advantages over that of Beeckmans et al [11]: (i) less reagents are used, hence less time and money are needed; (ii) the cost of MTT is less than half of nitroblue tetrazolium on the same weight basis; (iii) the cost of NADH is about one-third of NADP on the same weight basis; (iv) following the forward reaction with isocitrate as starting substrate can avoid activity inhibition encountered via ICL backward reaction [1,12,13]. In conclusion, a fast and sensitive activity staining method for ICL is presented.…”

“…However, the rapid diagnostic test was not suitable for locating ICL on polyacrylamide gels due to its heating step. Beeckmans et al [11] used succinate and glyoxylate as starting substrates for backward reaction of ICL to produce isocitrate, which was further converted to 2-oxo-glutarate by NADP-specific isocitrate dehydrogenase. The appearance of NADPH can be monitored by reacting with both phenazine methosufate and nitroblue tetrazolium and used as the ICL activity band.…”