Synthesis of Isobutyl-C-galactoside (IBCG) as an Isopropylthiogalactoside (IPTG) Substitute for Increased Induction of Protein Expression

Abstract

[reaction: see text] Addition of isopropyl-beta-d-thiogalactopyranoside (IPTG) to bacterial cultures is often used to induce expression of plasmid-based genes for the production of recombinant proteins under control of the lac promoter, but a simple method to circumvent the inherent instability of this compound has not been addressed experimentally. Herein we report the first synthesis of isobutyl-C-galactoside (IBCG), the C-glycoside analogue of IPTG, and show that IBCG is superior to IPTG in inducing protein expression over long induction times.

Synthesis of Cell‐Penetrating S‐Galactosyl–Oligoarginine Peptides as Inducers of Recombinant Protein Expression under the Control of lac Operator/Repressor Systems

“…After an 18 hours induction, the visible fluorescence of each culture was observed (irradiation at 365 nm, Figure 2), quantified by fluorescence spectrometry (excitation at 395 nm and emission at 509 nm), and normalized to the OD 600 nm of each culture (F/OD 600 nm ; Figure 2). [27,28] As expected, the normalized fluorescence of the culture was relatively large (F/OD 600 = 64) when IPTG was the inducer. When using the S-Gal-oligo(Arg) peptides as inducers, fluorescence at 509 nm was detected (F/OD 600 between 16 and 24), which is smaller than that found for IPTG, although larger than that for lactose (F/OD 600 = 5).…”

“…The fluorescence (F) of each culture, expressed as relative light units, was normalized to the number of cells (F/OD 600 nm ). [27,28] At least three independent experiments were carried out to check the reproducibility.…”

Synthesis of new S‐glycodendrimer toward activation of lac operon transcription for protein biosynthesis

“…The culture emission was determined using fluorescence spectrometry (Supporting Information); the fluorescent intensity (F) at 509 nm after excitation at 395 nm was normalized for the number of cells (OD 600 ), according to the reported protocol. 28,29 We used the F/OD 600 index to evaluate the expression level (Fig. 4).…”

Determination of thio-based additives for biopharmaceuticals by pulsed electrochemical detection following HPLC

“…The Sglycosidic linkage of IPTG is susceptible to chemical oxidation and cleavage reactions. No decomposition measurements in cellular media were carried out because samples were not available; however, it is known that the compound degrades under culture conditions and that more stable substitutes are currently being explored [3].…”

“…Isopropyl-␤-d-thiogalactopyranoside (IPTG) is used to trigger gene expression that is under control of the lac promoter for the overexpression of proteins [3]. IPTG is a chemical analog of galactose which cannot be cleaved by the enzyme ␤-galactosidase.…”