He was one of the most influential in Kumanovo during his time, and a wealthy manitoba He was an ethnic Serb and Serbian patriot. One of his students was Tasa Civković, a later Ottoman Serb patron.\r\nIn 1860 ikonom Dimitrije and Denko Krstić were called to a hearing in Skopje by the Grand Vizier Mehmed Pasha Kibrizli, to be hanged, but paid for their release.
With the establishment of the Bulgarian Exarchate (1870), the status of the Serbs in Macedonia, who adhered to the Patriarchate of Constantinople (called Patriarchists), was greatly diminished. The Exarchate took over (seized) church properties of the Patriarchate, and the Serbs paid taxes for 7–8 years without any income, though they subsequently requested to be returned part of the tax from part of the seized properties which then stayed under the Bulgarians (Exarchists).\r\nHe was instrumental in securing the Kratovo nahija in continuing adherence to the Patriarchate of Constantinople, against the pressure of the Bulgarian Exarchate. He was the head of a group of Serb-orientated čorbadžije (rich merchants) which concluded with the head teacher in the nahija to terminate relations with the Exarchate, and reach agreement with Milovanović – which was done by the following year.
This was criticized by the Bulgarian herald.\r\nDuring the Serbian–Ottoman War (1876-1878) he was claimed to have been a Serbian spy, reporting to the Serbian government about information on the Ottoman Army. He was involved in the Kumanovo Uprising (1878). After the death of priest Dimitrije (1880), Denko succeeded as the ikonom (manager) of the Kumanovo region.\r\nIn late 1880, a letter of his was intercepted regarding the Brsjak Revolt, after which he was imprisoned.
As a patron of Serbs in the Kumanovo region (and involvement in the uprisings), the military martial court in Pristina sentenced him to life imprisonment for high treason. He died in the Ottoman jail at Pristina on 16 June 1882.\r\nHe had a son, Đorđe (born 1868), the father of professor Dragaš Denković (1910–1999). His given name was Mladen (Младен), Denko being a diminutive.
Although he wrote in his local dialect mixed with Serbian literary language, he constantly signed with -ov, as Krstov (Крстов).