"Their continued stay in cabinet sends a message that Ramaphosa is inconsistent and fails go put the interests of South Africans above those of the ANC's big shots".
The local currency, which briefly fell below 15/$ in the early afternoon on Tuesday as uncertainty around the fate of Nhlanhal Nene lingered, ended up 1.8% stronger against the greenback, an indication of positive market reaction to the appointment of finance chief of the former SA Reserve Bank governor.
Last week, Mr Nene told a judge-led inquiry into the alleged influence of the Guptas, known as the Zondo commission, about meetings that he had previously denied.
Nene served as deputy finance minister and finance minister under former president Jacob Zuma.
Mboweni, who trained as an economist, served as head of the South African Reserve Bank for a decade until 2009 and for four years as labour minister in former President Nelson Mandela's cabinet.
The rand was 0.03% stronger at R14.5500 per dollar at 0700 GMT, having closed in NY at R14.5550.
Head of Interpol disappears during visit to China
But it does not have the power to send officers into countries to arrest individuals or issue arrest warrants. Interpol's defacto chief is its secretary general who is responsible for most of the operations.
Briefing the media, Ramaphosa said he had accepted Nhlanhla Nene's resignation.
"It's a measure of his character and commitment to the country that he has chose to resign in spite not being implicated in any wrongdoing", the president said.
Nene's departure from the finance portfolio comes as Treasury officials prepare to attend the International Monetary Fund's (IMF's) annual meeting in Bali and credit ratings agency Moody's is expected to do its next review of the country on Friday. Nene said during his testimony to the inquiry he was sacked in December 2015 for refusing to agree to Zuma's plans to spend billions of dollars on new nuclear plants.
It had received a battering under Mr Zuma's presidency.
Zuma ruled for nearly nine years before the governing African National Congress forced him to quit in February and replaced him with his 65-year-old deputy and party leader, Ramaphosa.
Ramaphosa has made clean governance and the kick-starting of an economy mired in recession top priorities.