Marketing and the Logic of Service: Value Facilitation, Value Creation and Co-creation, and Their Marketing Implications

The discussion of a service-dominant logic has made the findings of decades of service marketing research a topic of interest for marketing at large. Some fundamental aspects of the logic such as value creation and its marketing implications are more complex than they have been treated as so far and need to be further developed to serve marketing theory and practice well. Following the analysis in the present article it is argued that although customers are co-producers in service processes, according to the value-in-use notion adopted in the contemporary marketing and management literature they are fundamentally the creators of value for themselves. Furthermore, it is concluded that although by providing goods and services as input resources into customers’ consumption and value-generating processes firms are fundamentally value facilitators, interactions with customers that exist or can be created enable firms to engage themselves with their customers’ processes and thereby they become co-creators of value with their customers. As marketing implications it is observed that 1) the goal of marketing is to support customers’ value creation, 2) following a service logic and due to the existence of interactions where the firm’s and the customer’s processes merge into an integrated joint value creation process, the firm is not restricted to making value propositions only, but can directly and actively influence the customer’s value fulfilment as well and extend its marketing process to include activities during customer-firm interactions, and 3) although all goods and services are consumed as service, customers’ purchasing decisions can be expected to be dependant of whether they have the skills and interest to use a resource, such as a good, as service or want to buy extended market offerings including process-related elements. Finally, the analysis concludes with five service logic theses.

Towards Service Logic: The Unique Contribution of Value Co-Creation

The underpinning logic of value co-creation in service logic is analysed. It is observed that three of the ten foundational premises of the so-called service-dominant logic are problematic and do not support an understanding of value-co-creation and creation that is meaningful for theoretical development and decision making in business and marketing practice. Without a thorough understanding of the interaction concept, the locus and nature of value co-creation cannot be identified. Based on the analysis in the present article it is observed that a unique contribution of a service perspective on business (service logic) is not that customers always are co-creators of value, but that under certain circumstances the service provider gets opportunities to co-create value together with its customers. Finally, the three problematic premises are reformulated accordingly.

Studies on active site mutants of P-falciparum adenylosuccinate synthetase: Insights into enzyme catalysis and activation

Adenylosuccinate synthetase catalyzes a reversible reaction utilizing IMP, GTP and aspartate in the presence of Mg2+ to form adenylosuccinate, GDP and inorganic phosphate. Comparison of similarly liganded complexes of Plasmodium falciparum, mouse and Escherichia coil AdSS reveals H-bonding interactions involving nonconserved catalytic loop residues (Asn429, Lys62 and Thr307) that are unique to the parasite enzyme. Site-directed mutagenesis has been used to examine the role of these interactions in catalysis and structural organization of P. falciparum adenylosuccinate synthetase (PfAdSS). Mutation of Asn429 to Val, Lys62 to Leu and Thr307 to Val resulted in an increase in K-m values for IMP, GTP and aspartate, respectively along with a 5 fold drop in the k(cat) value for N429V mutant suggesting the role of these residues in ligand binding and/or catalysis. We have earlier shown that the glycolytic intermediate, fructose 1,6 bisphosphate, which is an inhibitor of mammalian AdSS is an activator of the parasite enzyme. Enzyme kinetics along with molecular docking suggests a mechanism for activation wherein F16BP seems to be binding to the Asp loop and inducing a conformation that facilitates aspartate binding to the enzyme active site. Like in other AdSS, a conserved arginine residue (Arg155) is involved in dimer crosstalk and interacts with IMP in the active site of the symmetry related subunit of PfAdSS. We also report on the iochemical characterization of the arginine mutants (R155L, R155K and R155A) which suggests that unlike in E. coil AdSS, Arg155 in PfAdSS influences both ligand binding and catalysis. (C) 2010 Elsevier B.V. All rights reserved.

A Cellular Array for Multivalued Logic Functions

An algebraic generalization of the well-known binary q-function array to a multivalued q-function array is presented. It is possible to associate tree-structure realizations for binary q-functions and multivalued q-functions. Synthesis of multivalued functions using this array is very simple

Source and target enzyme signature in serine protease inhibitor active site sequences

Amino acid sequences of proteinaceous proteinase inhibitors have been extensively analysed for deriving information regarding the molecular evolution and functional relationship of these proteins. These sequences have been grouped into several well defined families. It was found that the phylogeny constructed with the sequences corresponding to the exposed loop responsible for inhibition has several branches that resemble those obtained from comparisons using the entire sequence. The major branches of the unrooted tree corresponded to the families to which the inhibitors belonged. Further branching is related to the enzyme specificity of the inhibitor. Examination of the active site loop sequences of trypsin inhibitors revealed that there are strong preferences for specific amino acids at different positions of the loop. These preferences are inhibitor class specific. Inhibitors active against more than one enzyme occur within a class and confirm to class specific sequence in their loops. Hence, only a few positions in the loop seem to determine the specificity. The ability to inhibit the same enzyme by inhibitors that belong to different classes appears to be a result of convergent evolution

Serine Hydroxymethyltransferase from Mung Bean (Vigna radiata) Is Not a Pyridoxal-5'-Phosphate- Dependent Enzyme

Serine hydroxymethyltransferase from mammalian and bacterial sources is a pyridoxal-5'-phosphate-containing enzyme, but the requirement of pyridoxal-5'-phosphate for the activity of the enzyme from plant sources is not clear. The specific activity of serine hydroxymethyltransferase isolated from mung bean (Vigna radiata) seedlings in the presence and absence of pyridoxal-5'-phosphate was comparable at every step of the purification procedure. The mung bean enzyme did not show the characteristic visible absorbance spectrum of pyridoxal-5'-phosphate protein. Unlike the enzymes from sheep, monkey, and human liver, which were converted to the apoenzyme upon treatment with L-cysteine and dialysis, the mung bean enzyme similarly treated was fully active. Additional evidence in support of the suggestion that pyridoxal-5'-phosphate may not be required for the mung bean enzyme was the observation that pencillamine, a well-known inhibitor of pyridoxal-5'-phosphate enzymes, did not perturb the enzyme spectrum or inhibit the activity of mung bean serine hydroxymethyltransferase. The sheep liver enzyme upon interaction with O-amino-D-serine gave a fluorescence spectrum with an emission maximum at 455 nm when excited at 360 nm. A 100-fold higher concentration of mung bean enzyme-O-amino-D-serine complex did not yield a fluorescence spectrum. The following observations suggest that pyridoxal-5'-phosphate normally present as a coenzyme in serine hydroxymethyltransferase was probably replaced in mung bean serine hydroxymethyltransferase by a covalently bound carbonyl group: (a) inhibiton by phenylhydrazine and hydroxylamine, which could not be reversed by dialysis and or addition of pyridoxal-5'-phosphate; (b) irreversible inactivation by sodium borohydride; (c) a spectrum characteristic of a phenylhydrazone upon interaction with phenylhydrazine; and (d) the covalent labeling of the enzyme with substrate/product serine and glycine upon reduction with sodium borohydride. These results indicate that in mung bean serine hydroxymethyltransferase, a covalently bound carbonyl group has probably replaced the pyridoxal-5'-phosphate that is present in the mammalian and bacterial enzymes.

Plant aspartate transcarbamylase: An affinity chromatographic method for the purification of the enzyme from germinated seedlings

A simple and rapid affinity chromatographic method for the isolation of aspartate transcarbamylase from germinated seedlings of mung bean (Phaseolus aureus) was developed. A partially purified preparation of the enzyme was chromatographed on an affinity column containing aspartate linked to CNBr-activated Sepharose 4B. Aspartate transcarbamylase was specifically eluted from the column with 10 mImage aspartate or 0.5 Image KCl. The enzyme migrated as a single sharp band during disc electrophoresis at pH 8.6 on polyacrylamide gels. Electrophoresis of the sodium dodecyl sulfate-treated enzyme showed two distinct protein bands, suggesting that the mung bean aspartate transcarbamylase was made up of nonidentical subunits. Like the enzyme purified by conventional procedures, this enzyme preparation also exhibited positive homotropic interactions with carbamyl phosphate and negative heterotropic interactions with UMP. This method was extended to the purification of aspartate transcarbamylase from Lathyrus sativus, Eleucine coracona, and Trigonella foenum graecum.